Re: Why is "Memory split" Kconfig option only for EMBEDDED?
Hi! > So far all first-hand experiences I heard of were positive (i.e. I did > not get an emaail from anyone saying: It had a negative effect for me), > so I propose to apply the patch from Con Kolivas. The wording in the > description still very strongly recommends to not change that value, and > it's still dependent on EXPERIMENTAL. I append the patch just because There's a big difference between 'experimental' and 'known to broke obscure userspace apps'. -- Thanks for all the (sleeping) penguins. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: Why is Memory split Kconfig option only for EMBEDDED?
Hi! So far all first-hand experiences I heard of were positive (i.e. I did not get an emaail from anyone saying: It had a negative effect for me), so I propose to apply the patch from Con Kolivas. The wording in the description still very strongly recommends to not change that value, and it's still dependent on EXPERIMENTAL. I append the patch just because There's a big difference between 'experimental' and 'known to broke obscure userspace apps'. -- Thanks for all the (sleeping) penguins. - To unsubscribe from this list: send the line unsubscribe linux-kernel in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: Why is "Memory split" Kconfig option only for EMBEDDED?
On Thu, 2006-12-14 at 14:47 +, Pavel Machek wrote:
> Hi!
>
> > So far all first-hand experiences I heard of were positive (i.e. I did
> > not get an emaail from anyone saying: It had a negative effect for me),
> > so I propose to apply the patch from Con Kolivas. The wording in the
> > description still very strongly recommends to not change that value, and
> > it's still dependent on EXPERIMENTAL. I append the patch just because
>
> There's a big difference between 'experimental' and 'known to broke
> obscure userspace apps'.
True, but abusing EMBEDDED for "only do that if you know what you are
doing and if it breaks, you have to keep the pieces" is not good
either.
Some other places that seem to fall into the same category are
IPX_INTERN ("...This might break existing applications...") which is
neither EMBEDDED nor EXPERIMENTAL or RMW_INSNS ("...It is very likely
that this will cause serious problems on any Amiga...") that is
dependent on ADVANCED.
Anyway, perhaps I should just select EMBEDDED although I don't have a
small system (though a 6 year old 1Ghz K7 with 1GB mem might be
considered small by some people these days :-), and ignore all the other
options that pop up through this.
Best,
Norbert
-
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Re: Why is Memory split Kconfig option only for EMBEDDED?
On Thu, 2006-12-14 at 14:47 +, Pavel Machek wrote: Hi! So far all first-hand experiences I heard of were positive (i.e. I did not get an emaail from anyone saying: It had a negative effect for me), so I propose to apply the patch from Con Kolivas. The wording in the description still very strongly recommends to not change that value, and it's still dependent on EXPERIMENTAL. I append the patch just because There's a big difference between 'experimental' and 'known to broke obscure userspace apps'. True, but abusing EMBEDDED for only do that if you know what you are doing and if it breaks, you have to keep the pieces is not good either. Some other places that seem to fall into the same category are IPX_INTERN (...This might break existing applications...) which is neither EMBEDDED nor EXPERIMENTAL or RMW_INSNS (...It is very likely that this will cause serious problems on any Amiga...) that is dependent on ADVANCED. Anyway, perhaps I should just select EMBEDDED although I don't have a small system (though a 6 year old 1Ghz K7 with 1GB mem might be considered small by some people these days :-), and ignore all the other options that pop up through this. Best, Norbert - To unsubscribe from this list: send the line unsubscribe linux-kernel in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: Why is "Memory split" Kconfig option only for EMBEDDED?
> I have not had yet any problems with VMSPLIT_3G_OPT ever since I > used it -- which dates back to when it was a feature of Con > Kolivas's patchset (known as LOWMEM1G), [even] before it got > merged in mainline. > > (Excluding the cases Adrian Bunk listed: WINE, which I don't use, and > also 'some Java programs' which I have not seen.) Seconded. I have several servers with 1G of memory, and appreciate the option very much; I maintained it as a custom patch long before it became a CONFIG option. Turning on CONFIG_EMBEDDED makes it a bit annoying to be sure not to play with any of the other far more dangerous options that enables. (I suppose I could just maintain a local patch to remove that from Kconfig.) The last I remember hearing, the vm system wasn't very happy with highem much smaller than lowmem (128M/896M = 1/7) anyway. There's nothing wrong with a stern warning, but I'd think that disabling CONFIG_NET would break a lot more user-space programs, and that's not protected. How about the following (which also fixes a bug if you select VMSPLIT_2G and HIGHEM; with 64-bit page tables, the split must be on a 1G boundary): choice depends on EXPERIMENTAL prompt "Memory split" default VMSPLIT_3G help Select the desired split between kernel and user memory. If you are not absolutely sure what you are doing, leave this option alone! There are important efficiency reasons why the user address space and the kernel address space must both fit into the 4G linear virtual address space provided by the x86 architecture. Normally, Linux divides this into 3G for user virtual memory and 1G for kernel memory, which holds up to 896M of RAM plus all memory-mapped peripheral (e.g. PCI) devices. Excess RAM is ignored. If the "High memory support" options are enabled, the excess memory is available as "high memory", which can be used for user data, including file system caches, but not kernel data structures. However, accessing high memory from the kernel is slightly more costly than low memory, as it has to be mapped into the kernel address range first. This option lets systems choose to have a larger "low memory" space, either to avoid the need for high memory support entirely, or for workloads which require particularly large kernel data structures. The downside is that the available user address space is reduced. While most programs do not care, this is an incompatible change to the kernel binary interface, and must be made with caution. Some programs that process a lot of data will work more slowly or fail, and some programs that do clever things with virtual memory will crash immediately. In particular, changing this option from the default breaks valgrind version 3.1.0, VMware, and some Java virtual machines. config VMSPLIT_3G bool "Default 896MB lowmem (3G/1G user/kernel split)" config VMSPLIT_3G_OPT depends on !HIGHMEM bool "1G lowmem (2.75G/1.25G user/kernel split) CAUTION" config VMSPLIT_2G bool "1.875G lowmem (2G/2G user/kernel split) CAUTION" config VMSPLIT_2G_OPT depends on !HIGHMEM bool "2G lowmem (1.875G/2.125G user/kernel split) CAUTION" config VMSPLIT_1G bool "2.875G lowmem (1G/3G user/kernel split) CAUTION" config VMSPLIT_1G_OPT depends on !HIGHMEM bool "3G lowmem (896M/3.125G user/kernel split) CAUTION" endchoice config PAGE_OFFSET hex default 0xB000 if VMSPLIT_3G_OPT default 0x8000 if VMSPLIT_2G default 0x7800 if VMSPLIT_2G_OPT default 0x4000 if VMSPLIT_1G default 0x3800 if VMSPLIT_1G_OPT default 0xC000 (Copyright on the above abandoned to the public domain.) - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: Why is "Memory split" Kconfig option only for EMBEDDED?
On Sat, Dec 09, 2006 at 04:45:04PM +0100, Norbert Kiesel wrote: > On Sat, 2006-12-09 at 13:27 +0100, Alejandro Riveira Fernández wrote: > > El Wed, 6 Dec 2006 14:10:03 +0100 > > Adrian Bunk <[EMAIL PROTECTED]> escribió: > > > > > On Wed, Dec 06, 2006 at 01:19:08PM +0100, Norbert Kiesel wrote: > > > > On Wed, 2006-12-06 at 12:58 +0100, Arjan van de Ven wrote: > > > > > On Wed, 2006-12-06 at 12:42 +0100, Norbert Kiesel wrote: > > > > > > Hi, > > > > > > > > > > > > I remember reading on LKML some time ago that using VMSPLIT_3G_OPT > > > > > > would > > > > > > be optimal for a machine with exactly 1GB memory (like my current > > > > > > desktop). Why is that option only prompted for after selecting > > > > > > EMBEDDED > > > > > > (which I normally don't select for desktop machines > > > > > > > > > > because it changes the userspace ABI and has some other caveats > > > > > this > > > > > is not something you should muck with lightly > > > > > > > > > > > > > Hmm, but it's also marked EXPERIMENTAL. Would that not be the > > > > sufficient? Assuming I don't use any external/binary drivers and a > > > > self-compiled kernel w//o any additional patches: is there really any > > > > downside? > > > > > > - Wine doesn't work (I'm not sure about VMSPLIT_3G_OPT, but > > > VMSPLIT_2G definitely breaks Wine) > > > > I use VMSPLIT_3G_OPT=y and wine works just fine (only tested with one > > program). Edgy + 2.6.19-rc1 > > > > > > > > > - AFAIR some people reported problems with some Java programs > > > after fiddling with the vmsplit options > > > > > > EMBEDDED isn't exactly the right way to hide it, but the vmsplit options > > > aren't something you can safely change. > > > > > So far all first-hand experiences I heard of were positive (i.e. I did > not get an emaail from anyone saying: It had a negative effect for me), >... As I said, VMSPLIT_2G does break Wine for me. cu Adrian -- "Is there not promise of rain?" Ling Tan asked suddenly out of the darkness. There had been need of rain for many days. "Only a promise," Lao Er said. Pearl S. Buck - Dragon Seed - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: Why is "Memory split" Kconfig option only for EMBEDDED?
On Sat, 2006-12-09 at 13:27 +0100, Alejandro Riveira Fernández wrote: > El Wed, 6 Dec 2006 14:10:03 +0100 > Adrian Bunk <[EMAIL PROTECTED]> escribió: > > > On Wed, Dec 06, 2006 at 01:19:08PM +0100, Norbert Kiesel wrote: > > > On Wed, 2006-12-06 at 12:58 +0100, Arjan van de Ven wrote: > > > > On Wed, 2006-12-06 at 12:42 +0100, Norbert Kiesel wrote: > > > > > Hi, > > > > > > > > > > I remember reading on LKML some time ago that using VMSPLIT_3G_OPT > > > > > would > > > > > be optimal for a machine with exactly 1GB memory (like my current > > > > > desktop). Why is that option only prompted for after selecting > > > > > EMBEDDED > > > > > (which I normally don't select for desktop machines > > > > > > > > because it changes the userspace ABI and has some other caveats this > > > > is not something you should muck with lightly > > > > > > > > > > Hmm, but it's also marked EXPERIMENTAL. Would that not be the > > > sufficient? Assuming I don't use any external/binary drivers and a > > > self-compiled kernel w//o any additional patches: is there really any > > > downside? > > > > - Wine doesn't work (I'm not sure about VMSPLIT_3G_OPT, but > > VMSPLIT_2G definitely breaks Wine) > > I use VMSPLIT_3G_OPT=y and wine works just fine (only tested with one > program). Edgy + 2.6.19-rc1 > > > > > - AFAIR some people reported problems with some Java programs > > after fiddling with the vmsplit options > > > > EMBEDDED isn't exactly the right way to hide it, but the vmsplit options > > aren't something you can safely change. > > So far all first-hand experiences I heard of were positive (i.e. I did not get an emaail from anyone saying: It had a negative effect for me), so I propose to apply the patch from Con Kolivas. The wording in the description still very strongly recommends to not change that value, and it's still dependent on EXPERIMENTAL. I append the patch just because it's short, it's also available from http://www.kernel.org/pub/linux/kernel/people/ck/patches/2.6/2.6.19/2.6.19-ck2/patches/kconfig-expose_vmsplit_option.patch The options to alter the vmsplit to enable more lowmem are hidden behind the embedded option. Make it more exposed for -ck users and make the help menu more explicit about what each option means. Signed-off-by: Con Kolivas <[EMAIL PROTECTED]> --- arch/i386/Kconfig | 10 +- 1 file changed, 5 insertions(+), 5 deletions(-) Index: linux-2.6.19-ck2/arch/i386/Kconfig === --- linux-2.6.19-ck2.orig/arch/i386/Kconfig 2006-11-30 11:30:32.0 +1100 +++ linux-2.6.19-ck2/arch/i386/Kconfig 2006-12-09 09:01:36.0 +1100 @@ -500,7 +500,7 @@ endchoice choice depends on EXPERIMENTAL - prompt "Memory split" if EMBEDDED + prompt "Memory split" default VMSPLIT_3G help Select the desired split between kernel and user memory. @@ -519,14 +519,14 @@ choice option alone! config VMSPLIT_3G - bool "3G/1G user/kernel split" + bool "Default 896MB lowmem (3G/1G user/kernel split)" config VMSPLIT_3G_OPT depends on !HIGHMEM - bool "3G/1G user/kernel split (for full 1G low memory)" + bool "1GB lowmem (3G/1G user/kernel split)" config VMSPLIT_2G - bool "2G/2G user/kernel split" + bool "2GB lowmem (2G/2G user/kernel split)" config VMSPLIT_1G - bool "1G/3G user/kernel split" + bool "3GB lowmem (1G/3G user/kernel split)" endchoice config PAGE_OFFSET - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: Why is "Memory split" Kconfig option only for EMBEDDED?
El Wed, 6 Dec 2006 14:10:03 +0100 Adrian Bunk <[EMAIL PROTECTED]> escribió: > On Wed, Dec 06, 2006 at 01:19:08PM +0100, Norbert Kiesel wrote: > > On Wed, 2006-12-06 at 12:58 +0100, Arjan van de Ven wrote: > > > On Wed, 2006-12-06 at 12:42 +0100, Norbert Kiesel wrote: > > > > Hi, > > > > > > > > I remember reading on LKML some time ago that using VMSPLIT_3G_OPT would > > > > be optimal for a machine with exactly 1GB memory (like my current > > > > desktop). Why is that option only prompted for after selecting EMBEDDED > > > > (which I normally don't select for desktop machines > > > > > > because it changes the userspace ABI and has some other caveats this > > > is not something you should muck with lightly > > > > > > > Hmm, but it's also marked EXPERIMENTAL. Would that not be the > > sufficient? Assuming I don't use any external/binary drivers and a > > self-compiled kernel w//o any additional patches: is there really any > > downside? > > - Wine doesn't work (I'm not sure about VMSPLIT_3G_OPT, but > VMSPLIT_2G definitely breaks Wine) I use VMSPLIT_3G_OPT=y and wine works just fine (only tested with one program). Edgy + 2.6.19-rc1 > - AFAIR some people reported problems with some Java programs > after fiddling with the vmsplit options > > EMBEDDED isn't exactly the right way to hide it, but the vmsplit options > aren't something you can safely change. > > > > > cu > Adrian > - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: Why is Memory split Kconfig option only for EMBEDDED?
El Wed, 6 Dec 2006 14:10:03 +0100 Adrian Bunk [EMAIL PROTECTED] escribió: On Wed, Dec 06, 2006 at 01:19:08PM +0100, Norbert Kiesel wrote: On Wed, 2006-12-06 at 12:58 +0100, Arjan van de Ven wrote: On Wed, 2006-12-06 at 12:42 +0100, Norbert Kiesel wrote: Hi, I remember reading on LKML some time ago that using VMSPLIT_3G_OPT would be optimal for a machine with exactly 1GB memory (like my current desktop). Why is that option only prompted for after selecting EMBEDDED (which I normally don't select for desktop machines because it changes the userspace ABI and has some other caveats this is not something you should muck with lightly Hmm, but it's also marked EXPERIMENTAL. Would that not be the sufficient? Assuming I don't use any external/binary drivers and a self-compiled kernel w//o any additional patches: is there really any downside? - Wine doesn't work (I'm not sure about VMSPLIT_3G_OPT, but VMSPLIT_2G definitely breaks Wine) I use VMSPLIT_3G_OPT=y and wine works just fine (only tested with one program). Edgy + 2.6.19-rc1 - AFAIR some people reported problems with some Java programs after fiddling with the vmsplit options EMBEDDED isn't exactly the right way to hide it, but the vmsplit options aren't something you can safely change. /nk cu Adrian - To unsubscribe from this list: send the line unsubscribe linux-kernel in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: Why is Memory split Kconfig option only for EMBEDDED?
On Sat, 2006-12-09 at 13:27 +0100, Alejandro Riveira Fernández wrote: El Wed, 6 Dec 2006 14:10:03 +0100 Adrian Bunk [EMAIL PROTECTED] escribió: On Wed, Dec 06, 2006 at 01:19:08PM +0100, Norbert Kiesel wrote: On Wed, 2006-12-06 at 12:58 +0100, Arjan van de Ven wrote: On Wed, 2006-12-06 at 12:42 +0100, Norbert Kiesel wrote: Hi, I remember reading on LKML some time ago that using VMSPLIT_3G_OPT would be optimal for a machine with exactly 1GB memory (like my current desktop). Why is that option only prompted for after selecting EMBEDDED (which I normally don't select for desktop machines because it changes the userspace ABI and has some other caveats this is not something you should muck with lightly Hmm, but it's also marked EXPERIMENTAL. Would that not be the sufficient? Assuming I don't use any external/binary drivers and a self-compiled kernel w//o any additional patches: is there really any downside? - Wine doesn't work (I'm not sure about VMSPLIT_3G_OPT, but VMSPLIT_2G definitely breaks Wine) I use VMSPLIT_3G_OPT=y and wine works just fine (only tested with one program). Edgy + 2.6.19-rc1 - AFAIR some people reported problems with some Java programs after fiddling with the vmsplit options EMBEDDED isn't exactly the right way to hide it, but the vmsplit options aren't something you can safely change. So far all first-hand experiences I heard of were positive (i.e. I did not get an emaail from anyone saying: It had a negative effect for me), so I propose to apply the patch from Con Kolivas. The wording in the description still very strongly recommends to not change that value, and it's still dependent on EXPERIMENTAL. I append the patch just because it's short, it's also available from http://www.kernel.org/pub/linux/kernel/people/ck/patches/2.6/2.6.19/2.6.19-ck2/patches/kconfig-expose_vmsplit_option.patch The options to alter the vmsplit to enable more lowmem are hidden behind the embedded option. Make it more exposed for -ck users and make the help menu more explicit about what each option means. Signed-off-by: Con Kolivas [EMAIL PROTECTED] --- arch/i386/Kconfig | 10 +- 1 file changed, 5 insertions(+), 5 deletions(-) Index: linux-2.6.19-ck2/arch/i386/Kconfig === --- linux-2.6.19-ck2.orig/arch/i386/Kconfig 2006-11-30 11:30:32.0 +1100 +++ linux-2.6.19-ck2/arch/i386/Kconfig 2006-12-09 09:01:36.0 +1100 @@ -500,7 +500,7 @@ endchoice choice depends on EXPERIMENTAL - prompt Memory split if EMBEDDED + prompt Memory split default VMSPLIT_3G help Select the desired split between kernel and user memory. @@ -519,14 +519,14 @@ choice option alone! config VMSPLIT_3G - bool 3G/1G user/kernel split + bool Default 896MB lowmem (3G/1G user/kernel split) config VMSPLIT_3G_OPT depends on !HIGHMEM - bool 3G/1G user/kernel split (for full 1G low memory) + bool 1GB lowmem (3G/1G user/kernel split) config VMSPLIT_2G - bool 2G/2G user/kernel split + bool 2GB lowmem (2G/2G user/kernel split) config VMSPLIT_1G - bool 1G/3G user/kernel split + bool 3GB lowmem (1G/3G user/kernel split) endchoice config PAGE_OFFSET - To unsubscribe from this list: send the line unsubscribe linux-kernel in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: Why is Memory split Kconfig option only for EMBEDDED?
On Sat, Dec 09, 2006 at 04:45:04PM +0100, Norbert Kiesel wrote: On Sat, 2006-12-09 at 13:27 +0100, Alejandro Riveira Fernández wrote: El Wed, 6 Dec 2006 14:10:03 +0100 Adrian Bunk [EMAIL PROTECTED] escribió: On Wed, Dec 06, 2006 at 01:19:08PM +0100, Norbert Kiesel wrote: On Wed, 2006-12-06 at 12:58 +0100, Arjan van de Ven wrote: On Wed, 2006-12-06 at 12:42 +0100, Norbert Kiesel wrote: Hi, I remember reading on LKML some time ago that using VMSPLIT_3G_OPT would be optimal for a machine with exactly 1GB memory (like my current desktop). Why is that option only prompted for after selecting EMBEDDED (which I normally don't select for desktop machines because it changes the userspace ABI and has some other caveats this is not something you should muck with lightly Hmm, but it's also marked EXPERIMENTAL. Would that not be the sufficient? Assuming I don't use any external/binary drivers and a self-compiled kernel w//o any additional patches: is there really any downside? - Wine doesn't work (I'm not sure about VMSPLIT_3G_OPT, but VMSPLIT_2G definitely breaks Wine) I use VMSPLIT_3G_OPT=y and wine works just fine (only tested with one program). Edgy + 2.6.19-rc1 - AFAIR some people reported problems with some Java programs after fiddling with the vmsplit options EMBEDDED isn't exactly the right way to hide it, but the vmsplit options aren't something you can safely change. So far all first-hand experiences I heard of were positive (i.e. I did not get an emaail from anyone saying: It had a negative effect for me), ... As I said, VMSPLIT_2G does break Wine for me. cu Adrian -- Is there not promise of rain? Ling Tan asked suddenly out of the darkness. There had been need of rain for many days. Only a promise, Lao Er said. Pearl S. Buck - Dragon Seed - To unsubscribe from this list: send the line unsubscribe linux-kernel in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: Why is Memory split Kconfig option only for EMBEDDED?
I have not had yet any problems with VMSPLIT_3G_OPT ever since I used it -- which dates back to when it was a feature of Con Kolivas's patchset (known as LOWMEM1G), [even] before it got merged in mainline. (Excluding the cases Adrian Bunk listed: WINE, which I don't use, and also 'some Java programs' which I have not seen.) Seconded. I have several servers with 1G of memory, and appreciate the option very much; I maintained it as a custom patch long before it became a CONFIG option. Turning on CONFIG_EMBEDDED makes it a bit annoying to be sure not to play with any of the other far more dangerous options that enables. (I suppose I could just maintain a local patch to remove that from Kconfig.) The last I remember hearing, the vm system wasn't very happy with highem much smaller than lowmem (128M/896M = 1/7) anyway. There's nothing wrong with a stern warning, but I'd think that disabling CONFIG_NET would break a lot more user-space programs, and that's not protected. How about the following (which also fixes a bug if you select VMSPLIT_2G and HIGHEM; with 64-bit page tables, the split must be on a 1G boundary): choice depends on EXPERIMENTAL prompt Memory split default VMSPLIT_3G help Select the desired split between kernel and user memory. If you are not absolutely sure what you are doing, leave this option alone! There are important efficiency reasons why the user address space and the kernel address space must both fit into the 4G linear virtual address space provided by the x86 architecture. Normally, Linux divides this into 3G for user virtual memory and 1G for kernel memory, which holds up to 896M of RAM plus all memory-mapped peripheral (e.g. PCI) devices. Excess RAM is ignored. If the High memory support options are enabled, the excess memory is available as high memory, which can be used for user data, including file system caches, but not kernel data structures. However, accessing high memory from the kernel is slightly more costly than low memory, as it has to be mapped into the kernel address range first. This option lets systems choose to have a larger low memory space, either to avoid the need for high memory support entirely, or for workloads which require particularly large kernel data structures. The downside is that the available user address space is reduced. While most programs do not care, this is an incompatible change to the kernel binary interface, and must be made with caution. Some programs that process a lot of data will work more slowly or fail, and some programs that do clever things with virtual memory will crash immediately. In particular, changing this option from the default breaks valgrind version 3.1.0, VMware, and some Java virtual machines. config VMSPLIT_3G bool Default 896MB lowmem (3G/1G user/kernel split) config VMSPLIT_3G_OPT depends on !HIGHMEM bool 1G lowmem (2.75G/1.25G user/kernel split) CAUTION config VMSPLIT_2G bool 1.875G lowmem (2G/2G user/kernel split) CAUTION config VMSPLIT_2G_OPT depends on !HIGHMEM bool 2G lowmem (1.875G/2.125G user/kernel split) CAUTION config VMSPLIT_1G bool 2.875G lowmem (1G/3G user/kernel split) CAUTION config VMSPLIT_1G_OPT depends on !HIGHMEM bool 3G lowmem (896M/3.125G user/kernel split) CAUTION endchoice config PAGE_OFFSET hex default 0xB000 if VMSPLIT_3G_OPT default 0x8000 if VMSPLIT_2G default 0x7800 if VMSPLIT_2G_OPT default 0x4000 if VMSPLIT_1G default 0x3800 if VMSPLIT_1G_OPT default 0xC000 (Copyright on the above abandoned to the public domain.) - To unsubscribe from this list: send the line unsubscribe linux-kernel in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: Why is "Memory split" Kconfig option only for EMBEDDED?
On Dec 6 2006 22:00, Jan Engelhardt wrote: > >I have not had yet any problems with VMSPLIT_3G_OPT ever since I >used it -- which dates back to when it was a feature of Con >Kolivas's patchset (known as LOWMEM1G), [even] before it got >merged in mainline. (Excluding the cases Adrian Bunk listed: WINE, which I don't use, and also 'some Java programs' which I have not seen.) -`J' -- - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: Why is "Memory split" Kconfig option only for EMBEDDED?
On Dec 6 2006 14:36, Norbert Kiesel wrote: >On Wed, 2006-12-06 at 13:45 +0100, Arjan van de Ven wrote: >> On Wed, 2006-12-06 at 13:19 +0100, Norbert Kiesel wrote: >> > On Wed, 2006-12-06 at 12:58 +0100, Arjan van de Ven wrote: >> > > On Wed, 2006-12-06 at 12:42 +0100, Norbert Kiesel wrote: >> > > > Hi, >> > > > >> > > > I remember reading on LKML some time ago that using >> > > > VMSPLIT_3G_OPT would be optimal for a machine with >> > > > exactly 1GB memory (like my current desktop). Why is >> > > > that option only prompted for after selecting EMBEDDED >> > > > (which I normally don't select for desktop machines >> > > >> > > because it changes the userspace ABI and has some other >> > > caveats this is not something you should muck with >> > > lightly >> > >> > Hmm, but it's also marked EXPERIMENTAL. Would that not be >> > the sufficient? Assuming I don't use any external/binary >> > drivers and a self-compiled kernel w//o any additional >> > patches: is there really any downside? >> >> I said *userspace ABI*. You're changing something that >> userspace has known about and was documented since the start >> of Linux. So userspace application binaries can break, and at >> least you're changing the rules on them. That's fine if you >> know what you're doing.. but in a general system... not a >> good default, hence the EMBEDDED. > >Thanks for the reply. I was not asking to change the default, I >just want to see the option in e.g. menuconfig. And the help >text already has a very strong advise to leave it at >VMSPLIT_3G. I have not had yet any problems with VMSPLIT_3G_OPT ever since I used it -- which dates back to when it was a feature of Con Kolivas's patchset (known as LOWMEM1G), [even] before it got merged in mainline. It only seem to break the VMware compilation process, but what they do in the makefiles is not really standard anyhow. >Anyway, I don't want to stress this further: I'm happy enough with my >Kconfig that has "if EMBEDDED" removed for the prompt. -`J' -- - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: Why is "Memory split" Kconfig option only for EMBEDDED?
On Wed, 2006-12-06 at 13:45 +0100, Arjan van de Ven wrote: > On Wed, 2006-12-06 at 13:19 +0100, Norbert Kiesel wrote: > > On Wed, 2006-12-06 at 12:58 +0100, Arjan van de Ven wrote: > > > On Wed, 2006-12-06 at 12:42 +0100, Norbert Kiesel wrote: > > > > Hi, > > > > > > > > I remember reading on LKML some time ago that using VMSPLIT_3G_OPT would > > > > be optimal for a machine with exactly 1GB memory (like my current > > > > desktop). Why is that option only prompted for after selecting EMBEDDED > > > > (which I normally don't select for desktop machines > > > > > > because it changes the userspace ABI and has some other caveats this > > > is not something you should muck with lightly > > > > > > > Hmm, but it's also marked EXPERIMENTAL. Would that not be the > > sufficient? Assuming I don't use any external/binary drivers and a > > self-compiled kernel w//o any additional patches: is there really any > > downside? > > I said *userspace ABI*. You're changing something that userspace has > known about and was documented since the start of Linux. So userspace > application binaries can break, and at least you're changing the rules > on them. That's fine if you know what you're doing.. but in a general > system... not a good default, hence the EMBEDDED. Thanks for the reply. I was not asking to change the default, I just want to see the option in e.g. menuconfig. And the help text already has a very strong advise to leave it at VMSPLIT_3G. Anyway, I don't want to stress this further: I'm happy enough with my Kconfig that has "if EMBEDDED" removed for the prompt. Best, Norbert - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: Why is "Memory split" Kconfig option only for EMBEDDED?
On Wed, Dec 06, 2006 at 01:19:08PM +0100, Norbert Kiesel wrote: > On Wed, 2006-12-06 at 12:58 +0100, Arjan van de Ven wrote: > > On Wed, 2006-12-06 at 12:42 +0100, Norbert Kiesel wrote: > > > Hi, > > > > > > I remember reading on LKML some time ago that using VMSPLIT_3G_OPT would > > > be optimal for a machine with exactly 1GB memory (like my current > > > desktop). Why is that option only prompted for after selecting EMBEDDED > > > (which I normally don't select for desktop machines > > > > because it changes the userspace ABI and has some other caveats this > > is not something you should muck with lightly > > > > Hmm, but it's also marked EXPERIMENTAL. Would that not be the > sufficient? Assuming I don't use any external/binary drivers and a > self-compiled kernel w//o any additional patches: is there really any > downside? - Wine doesn't work (I'm not sure about VMSPLIT_3G_OPT, but VMSPLIT_2G definitely breaks Wine) - AFAIR some people reported problems with some Java programs after fiddling with the vmsplit options EMBEDDED isn't exactly the right way to hide it, but the vmsplit options aren't something you can safely change. > cu Adrian -- "Is there not promise of rain?" Ling Tan asked suddenly out of the darkness. There had been need of rain for many days. "Only a promise," Lao Er said. Pearl S. Buck - Dragon Seed - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: Why is "Memory split" Kconfig option only for EMBEDDED?
On Wed, 2006-12-06 at 13:19 +0100, Norbert Kiesel wrote: > On Wed, 2006-12-06 at 12:58 +0100, Arjan van de Ven wrote: > > On Wed, 2006-12-06 at 12:42 +0100, Norbert Kiesel wrote: > > > Hi, > > > > > > I remember reading on LKML some time ago that using VMSPLIT_3G_OPT would > > > be optimal for a machine with exactly 1GB memory (like my current > > > desktop). Why is that option only prompted for after selecting EMBEDDED > > > (which I normally don't select for desktop machines > > > > because it changes the userspace ABI and has some other caveats this > > is not something you should muck with lightly > > > > Hmm, but it's also marked EXPERIMENTAL. Would that not be the > sufficient? Assuming I don't use any external/binary drivers and a > self-compiled kernel w//o any additional patches: is there really any > downside? I said *userspace ABI*. You're changing something that userspace has known about and was documented since the start of Linux. So userspace application binaries can break, and at least you're changing the rules on them. That's fine if you know what you're doing.. but in a general system... not a good default, hence the EMBEDDED. I assumed entirely that you're not using binary drivers, those are just horrid in the first place :) -- if you want to mail me at work (you don't), use arjan (at) linux.intel.com Test the interaction between Linux and your BIOS via http://www.linuxfirmwarekit.org - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: Why is "Memory split" Kconfig option only for EMBEDDED?
On Wed, 2006-12-06 at 12:58 +0100, Arjan van de Ven wrote: > On Wed, 2006-12-06 at 12:42 +0100, Norbert Kiesel wrote: > > Hi, > > > > I remember reading on LKML some time ago that using VMSPLIT_3G_OPT would > > be optimal for a machine with exactly 1GB memory (like my current > > desktop). Why is that option only prompted for after selecting EMBEDDED > > (which I normally don't select for desktop machines > > because it changes the userspace ABI and has some other caveats this > is not something you should muck with lightly > Hmm, but it's also marked EXPERIMENTAL. Would that not be the sufficient? Assuming I don't use any external/binary drivers and a self-compiled kernel w//o any additional patches: is there really any downside? - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: Why is "Memory split" Kconfig option only for EMBEDDED?
On Wed, 2006-12-06 at 12:42 +0100, Norbert Kiesel wrote: > Hi, > > I remember reading on LKML some time ago that using VMSPLIT_3G_OPT would > be optimal for a machine with exactly 1GB memory (like my current > desktop). Why is that option only prompted for after selecting EMBEDDED > (which I normally don't select for desktop machines because it changes the userspace ABI and has some other caveats this is not something you should muck with lightly -- if you want to mail me at work (you don't), use arjan (at) linux.intel.com Test the interaction between Linux and your BIOS via http://www.linuxfirmwarekit.org - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Why is "Memory split" Kconfig option only for EMBEDDED?
Hi, I remember reading on LKML some time ago that using VMSPLIT_3G_OPT would be optimal for a machine with exactly 1GB memory (like my current desktop). Why is that option only prompted for after selecting EMBEDDED (which I normally don't select for desktop machines)? Best, Norbert - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Why is Memory split Kconfig option only for EMBEDDED?
Hi, I remember reading on LKML some time ago that using VMSPLIT_3G_OPT would be optimal for a machine with exactly 1GB memory (like my current desktop). Why is that option only prompted for after selecting EMBEDDED (which I normally don't select for desktop machines)? Best, Norbert - To unsubscribe from this list: send the line unsubscribe linux-kernel in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: Why is Memory split Kconfig option only for EMBEDDED?
On Wed, 2006-12-06 at 12:42 +0100, Norbert Kiesel wrote: Hi, I remember reading on LKML some time ago that using VMSPLIT_3G_OPT would be optimal for a machine with exactly 1GB memory (like my current desktop). Why is that option only prompted for after selecting EMBEDDED (which I normally don't select for desktop machines because it changes the userspace ABI and has some other caveats this is not something you should muck with lightly -- if you want to mail me at work (you don't), use arjan (at) linux.intel.com Test the interaction between Linux and your BIOS via http://www.linuxfirmwarekit.org - To unsubscribe from this list: send the line unsubscribe linux-kernel in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: Why is Memory split Kconfig option only for EMBEDDED?
On Wed, 2006-12-06 at 12:58 +0100, Arjan van de Ven wrote: On Wed, 2006-12-06 at 12:42 +0100, Norbert Kiesel wrote: Hi, I remember reading on LKML some time ago that using VMSPLIT_3G_OPT would be optimal for a machine with exactly 1GB memory (like my current desktop). Why is that option only prompted for after selecting EMBEDDED (which I normally don't select for desktop machines because it changes the userspace ABI and has some other caveats this is not something you should muck with lightly Hmm, but it's also marked EXPERIMENTAL. Would that not be the sufficient? Assuming I don't use any external/binary drivers and a self-compiled kernel w//o any additional patches: is there really any downside? /nk - To unsubscribe from this list: send the line unsubscribe linux-kernel in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: Why is Memory split Kconfig option only for EMBEDDED?
On Wed, 2006-12-06 at 13:19 +0100, Norbert Kiesel wrote: On Wed, 2006-12-06 at 12:58 +0100, Arjan van de Ven wrote: On Wed, 2006-12-06 at 12:42 +0100, Norbert Kiesel wrote: Hi, I remember reading on LKML some time ago that using VMSPLIT_3G_OPT would be optimal for a machine with exactly 1GB memory (like my current desktop). Why is that option only prompted for after selecting EMBEDDED (which I normally don't select for desktop machines because it changes the userspace ABI and has some other caveats this is not something you should muck with lightly Hmm, but it's also marked EXPERIMENTAL. Would that not be the sufficient? Assuming I don't use any external/binary drivers and a self-compiled kernel w//o any additional patches: is there really any downside? I said *userspace ABI*. You're changing something that userspace has known about and was documented since the start of Linux. So userspace application binaries can break, and at least you're changing the rules on them. That's fine if you know what you're doing.. but in a general system... not a good default, hence the EMBEDDED. I assumed entirely that you're not using binary drivers, those are just horrid in the first place :) -- if you want to mail me at work (you don't), use arjan (at) linux.intel.com Test the interaction between Linux and your BIOS via http://www.linuxfirmwarekit.org - To unsubscribe from this list: send the line unsubscribe linux-kernel in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: Why is Memory split Kconfig option only for EMBEDDED?
On Wed, Dec 06, 2006 at 01:19:08PM +0100, Norbert Kiesel wrote: On Wed, 2006-12-06 at 12:58 +0100, Arjan van de Ven wrote: On Wed, 2006-12-06 at 12:42 +0100, Norbert Kiesel wrote: Hi, I remember reading on LKML some time ago that using VMSPLIT_3G_OPT would be optimal for a machine with exactly 1GB memory (like my current desktop). Why is that option only prompted for after selecting EMBEDDED (which I normally don't select for desktop machines because it changes the userspace ABI and has some other caveats this is not something you should muck with lightly Hmm, but it's also marked EXPERIMENTAL. Would that not be the sufficient? Assuming I don't use any external/binary drivers and a self-compiled kernel w//o any additional patches: is there really any downside? - Wine doesn't work (I'm not sure about VMSPLIT_3G_OPT, but VMSPLIT_2G definitely breaks Wine) - AFAIR some people reported problems with some Java programs after fiddling with the vmsplit options EMBEDDED isn't exactly the right way to hide it, but the vmsplit options aren't something you can safely change. /nk cu Adrian -- Is there not promise of rain? Ling Tan asked suddenly out of the darkness. There had been need of rain for many days. Only a promise, Lao Er said. Pearl S. Buck - Dragon Seed - To unsubscribe from this list: send the line unsubscribe linux-kernel in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: Why is Memory split Kconfig option only for EMBEDDED?
On Wed, 2006-12-06 at 13:45 +0100, Arjan van de Ven wrote: On Wed, 2006-12-06 at 13:19 +0100, Norbert Kiesel wrote: On Wed, 2006-12-06 at 12:58 +0100, Arjan van de Ven wrote: On Wed, 2006-12-06 at 12:42 +0100, Norbert Kiesel wrote: Hi, I remember reading on LKML some time ago that using VMSPLIT_3G_OPT would be optimal for a machine with exactly 1GB memory (like my current desktop). Why is that option only prompted for after selecting EMBEDDED (which I normally don't select for desktop machines because it changes the userspace ABI and has some other caveats this is not something you should muck with lightly Hmm, but it's also marked EXPERIMENTAL. Would that not be the sufficient? Assuming I don't use any external/binary drivers and a self-compiled kernel w//o any additional patches: is there really any downside? I said *userspace ABI*. You're changing something that userspace has known about and was documented since the start of Linux. So userspace application binaries can break, and at least you're changing the rules on them. That's fine if you know what you're doing.. but in a general system... not a good default, hence the EMBEDDED. Thanks for the reply. I was not asking to change the default, I just want to see the option in e.g. menuconfig. And the help text already has a very strong advise to leave it at VMSPLIT_3G. Anyway, I don't want to stress this further: I'm happy enough with my Kconfig that has if EMBEDDED removed for the prompt. Best, Norbert - To unsubscribe from this list: send the line unsubscribe linux-kernel in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: Why is Memory split Kconfig option only for EMBEDDED?
On Dec 6 2006 14:36, Norbert Kiesel wrote: On Wed, 2006-12-06 at 13:45 +0100, Arjan van de Ven wrote: On Wed, 2006-12-06 at 13:19 +0100, Norbert Kiesel wrote: On Wed, 2006-12-06 at 12:58 +0100, Arjan van de Ven wrote: On Wed, 2006-12-06 at 12:42 +0100, Norbert Kiesel wrote: Hi, I remember reading on LKML some time ago that using VMSPLIT_3G_OPT would be optimal for a machine with exactly 1GB memory (like my current desktop). Why is that option only prompted for after selecting EMBEDDED (which I normally don't select for desktop machines because it changes the userspace ABI and has some other caveats this is not something you should muck with lightly Hmm, but it's also marked EXPERIMENTAL. Would that not be the sufficient? Assuming I don't use any external/binary drivers and a self-compiled kernel w//o any additional patches: is there really any downside? I said *userspace ABI*. You're changing something that userspace has known about and was documented since the start of Linux. So userspace application binaries can break, and at least you're changing the rules on them. That's fine if you know what you're doing.. but in a general system... not a good default, hence the EMBEDDED. Thanks for the reply. I was not asking to change the default, I just want to see the option in e.g. menuconfig. And the help text already has a very strong advise to leave it at VMSPLIT_3G. I have not had yet any problems with VMSPLIT_3G_OPT ever since I used it -- which dates back to when it was a feature of Con Kolivas's patchset (known as LOWMEM1G), [even] before it got merged in mainline. It only seem to break the VMware compilation process, but what they do in the makefiles is not really standard anyhow. Anyway, I don't want to stress this further: I'm happy enough with my Kconfig that has if EMBEDDED removed for the prompt. -`J' -- - To unsubscribe from this list: send the line unsubscribe linux-kernel in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: Why is Memory split Kconfig option only for EMBEDDED?
On Dec 6 2006 22:00, Jan Engelhardt wrote: I have not had yet any problems with VMSPLIT_3G_OPT ever since I used it -- which dates back to when it was a feature of Con Kolivas's patchset (known as LOWMEM1G), [even] before it got merged in mainline. (Excluding the cases Adrian Bunk listed: WINE, which I don't use, and also 'some Java programs' which I have not seen.) -`J' -- - To unsubscribe from this list: send the line unsubscribe linux-kernel in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
