[fbsd_questions] i386 vs amd64, on intel_64
howdy, y'all --- these may be stupid questions and, if so, i am prepared to slap my forehead with the palm of my hand. i recently acquired my first batch of intel cpus with 64_bit integer registers [ celeron 440 ], specifically for the 16 registers and the potential for a truly_gargantuan datasize. intel has called this many things, currently intel 64 architecture. to me, this is just a bigger, faster 386, just like my 486 and several flavors of pentium [ now, all retired ]. i have never owned an amd cpu. this may be the source of my confusion. what prompted my recent searches was the observation, while working on my killer_app, in machine/types.h, as i recall, that the size of an intptr is 32_bits. [ i am aware of the gcc double_integer implementation of 64_bit data_integers. that is not the issue; i want big memory. ] i want my app to exist in two sizes, small [ 8_, 16_ and 32_bit integers and 32_bit pointers ] and large [ 8_, 16_, 32_ and 64_bit integers and 48_bit pointers ], the choice between the two being made by my users, according to their needs. my objective is to produce both versions, simultaneously. so, i have been looking at many pages, mostly at freebsd.org [ http and ftp ] and gcc.gnu.org, as well as some others [ release notes, in particular ]. the last question is the big one. consider a dvd_image [ to pick an approach ] of a release to be found on ftp.freebsd.org. q:if the release_name includes the string i386, am i restricted to 8 32_bit registers and 32_bit pointers, notwithstanding its installation on an intel_64 platform ? next, from what i have been reading, those releases whose names contain amd64 not only are for amd cpus, but, also, are for the intel_64 variant [ no doubt, probing the cpu for its feature_set ]. q:if i install an amd64 version on an intel_64 platform, am i restricted to 16 64_bit registers and 48_bit pointers or can i compile for both cpu_models [ perhaps, with nothing more complicated than a compiler option ] ? please cc. in advance, thanks big_time. rob ___ freebsd-questions@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-questions To unsubscribe, send any mail to freebsd-questions-unsubscr...@freebsd.org
Re: [fbsd_questions] i386 vs amd64, on intel_64
On Mon, Oct 4, 2010 at 12:51 PM, spellberg_robert email...@emailrob.com wrote: q: if i install an amd64 version on an intel_64 platform, am i restricted to 16 64_bit registers and 48_bit pointers or can i compile for both cpu_models [ perhaps, with nothing more complicated than a compiler option ] ? Take a look at gcc's -m32 and -m64 options. ___ freebsd-questions@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-questions To unsubscribe, send any mail to freebsd-questions-unsubscr...@freebsd.org
Re: [fbsd_questions] i386 vs amd64, on intel_64
hmmm ..., you did not answer the question that i asked. per your statement, on i386, amd64 or both ? David Brodbeck wrote: On Mon, Oct 4, 2010 at 12:51 PM, spellberg_robert email...@emailrob.com wrote: q:if i install an amd64 version on an intel_64 platform, am i restricted to 16 64_bit registers and 48_bit pointers or can i compile for both cpu_models [ perhaps, with nothing more complicated than a compiler option ] ? Take a look at gcc's -m32 and -m64 options. ___ freebsd-questions@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-questions To unsubscribe, send any mail to freebsd-questions-unsubscr...@freebsd.org
Re: [fbsd_questions] i386 vs amd64, on intel_64
On a 64-bit system, if you build a binary with the -m32 flag, it should run on both i386 and x86-64 systems. A binary built with -m64 will only run on x86-64. Does that help? On Mon, Oct 4, 2010 at 1:45 PM, spellberg_robert email...@emailrob.com wrote: hmmm ..., you did not answer the question that i asked. per your statement, on i386, amd64 or both ? David Brodbeck wrote: On Mon, Oct 4, 2010 at 12:51 PM, spellberg_robert email...@emailrob.com wrote: q: if i install an amd64 version on an intel_64 platform, am i restricted to 16 64_bit registers and 48_bit pointers or can i compile for both cpu_models [ perhaps, with nothing more complicated than a compiler option ] ? Take a look at gcc's -m32 and -m64 options. ___ freebsd-questions@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-questions To unsubscribe, send any mail to freebsd-questions-unsubscr...@freebsd.org
Re: [fbsd_questions] i386 vs amd64, on intel_64
spellberg_robert wrote: [snip] consider a dvd_image [ to pick an approach ] of a release to be found on ftp.freebsd.org. q:if the release_name includes the string i386, am i restricted to 8 32_bit registers and 32_bit pointers, notwithstanding its installation on an intel_64 platform ? I am certainly not an expert, and if I am interpreting the question correctly I believe the answer here would be yes. x86 processors of today can run either 32 bit or 64 bit OS. For example, you could install a 32 bit Windows XP and it would run as 32 bit even thought the processor has 64 bit capability. The restriction you are asking about here would be as a result of using a 32 bit OS and not because of processor capabilities. next, from what i have been reading, those releases whose names contain amd64 not only are for amd cpus, but, also, are for the intel_64 variant [ no doubt, probing the cpu for its feature_set ]. q:if i install an amd64 version on an intel_64 platform, am i restricted to 16 64_bit registers and 48_bit pointers or can i compile for both cpu_models [ perhaps, with nothing more complicated than a compiler option [ ] ? The amd64 stuck primarily because the 64 bit extensions were initially pioneered by AMD, and subsequently copied by Intel. Generally speaking, for the most part it is possible to run 32 bit binaries on a 64 bit OS installed to 64 bit x86 CPU hardware. Another Windows example: Let's say you have 64 bit version of Windows installed. It can run 32 bit apps using WoW, or Windows on Windows. amd64 processor can execute either 32 bit or 64 bit simultaneously providing there are libraries contained within the OS to facilitate this. You just wouldn't really want to do this because it is slow. I do not know enough about this as I have never had a need, but I think similar facilities exist in FreeBSD. You can install amd64 to a 64 bit CPU and still execute 32 bit software using a 32 compatibility library set. Look at the GENERIC kernel config file for amd64 and you will see a line like this: options COMPAT_FREEBSD32# Compatible with i386 binaries You need to have the 32 bit library set built and installed. Investigate this particular subject for further (and better) explanation. It isn't so much a matter of compiling an app for both models as it is where they will run. You cannot compile an app as 64 bit and run it on an i386 OS install, whether or not the CPU is 64 bit. But with the help of 32 bit compatibility libs you _can_ run a 32 bit binary on a 64 bit OS installed to a 64 bit processor. -Mike ___ freebsd-questions@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-questions To unsubscribe, send any mail to freebsd-questions-unsubscr...@freebsd.org
Re: [fbsd_questions] i386 vs amd64, on intel_64
In the last episode (Oct 04), David Brodbeck said: On a 64-bit system, if you build a binary with the -m32 flag, it should run on both i386 and x86-64 systems. A binary built with -m64 will only run on x86-64. Does that help? Actually, -m32 on amd64 won't generate usable binaries, since /usr/include/machine/* are all amd64 headers and you end up with things like struct FILE with wrong-size elements. There was a thread a few weeks ago discussing this. If you need to generate 32-bit executables, you'll need to do it inside an all-32-bit chroot or a virtual machine. -- Dan Nelson dnel...@allantgroup.com ___ freebsd-questions@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-questions To unsubscribe, send any mail to freebsd-questions-unsubscr...@freebsd.org
Re: [fbsd_questions] i386 vs amd64, on intel_64
aha ! this relates to what i found in machine/types.h, on my existing i386 version of freebsd on my intel_64 hardware platform. i will look into the questions archive. meanwhile, back at the ranch, does this mean that i need the amd64 version of freebsd to get the right headers ? Dan Nelson wrote: In the last episode (Oct 04), David Brodbeck said: On a 64-bit system, if you build a binary with the -m32 flag, it should run on both i386 and x86-64 systems. A binary built with -m64 will only run on x86-64. Does that help? Actually, -m32 on amd64 won't generate usable binaries, since /usr/include/machine/* are all amd64 headers and you end up with things like struct FILE with wrong-size elements. There was a thread a few weeks ago discussing this. If you need to generate 32-bit executables, you'll need to do it inside an all-32-bit chroot or a virtual machine. ___ freebsd-questions@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-questions To unsubscribe, send any mail to freebsd-questions-unsubscr...@freebsd.org
Re: [fbsd_questions] i386 vs amd64, on intel_64
well, i looked at questions back to the beginning of august. on aug_09 i found a thread that suggests the following questions. for a given release of freebsd, q:is it that the version labeled i386 contains only 32_bit headers and source, which creates the 32_bit version of freebsd, as well as 32_bit versions of what i write, which will run as 32_bit code on either i_386, intel_64 or amd_64 ? q:is it that the version labeled amd64 contains only 64_bit headers and source, which creates the 64_bit version of freebsd, as well as 64_bit versions of what i write, which will run as 64_bit code on the intel_64 and the amd_64, but, not the i_386 ? q:if a i386 version is installed on an intel_64 platform, then the pointers are 32_bits_wide, no matter what ? q:if i want to produce both 32_bit and 64_bit versions of my killer_app, then i need two machines, one a 32_bit or a 64_bit running i386, the other --only-- a 64_bit running amd64 ? q:given that i have intel_64 hardware, do i need to start acquiring the amd64 versions of the releases, rather_than / in_addition_to the i386 versions ? q:given that --i-- am committed to 64_bit hardware, perhaps, i should give up on the i386 versions of the releases and require my users to spend us$_300 on 64_bit hardware [ it would save a large number of conditional_compilation directives; nudge_nudge, wink_wink, say no more ] ? again, i thank you for your assistance. rob Dan Nelson wrote: In the last episode (Oct 04), David Brodbeck said: On a 64-bit system, if you build a binary with the -m32 flag, it should run on both i386 and x86-64 systems. A binary built with -m64 will only run on x86-64. Does that help? Actually, -m32 on amd64 won't generate usable binaries, since /usr/include/machine/* are all amd64 headers and you end up with things like struct FILE with wrong-size elements. There was a thread a few weeks ago discussing this. If you need to generate 32-bit executables, you'll need to do it inside an all-32-bit chroot or a virtual machine. ___ freebsd-questions@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-questions To unsubscribe, send any mail to freebsd-questions-unsubscr...@freebsd.org
Re: [fbsd_questions] i386 vs amd64, on intel_64
In the last episode (Oct 05), spellberg_robert said: well, i looked at questions back to the beginning of august. on aug_09 i found a thread that suggests the following questions. You might want to just use i386 and amd64 instead of making up your own terminology (i_386, intel_64, amd_64, etc). Note that Intel has chips that support two competing 64-bit instruction sets: ia64, which is used by their Itanium line, and amd64, which originated on AMD chips but Intel adopted for their 64-bit-capable x86 chips (Xeon, Core etc). I'll assume that any time you say intel_64 or amd_64 you really mean amd64, since nobody uses Itaniums :) for a given release of freebsd, q:is it that the version labeled i386 contains only 32_bit headers and source, which creates the 32_bit version of freebsd, as well as 32_bit versions of what i write, which will run as 32_bit code on either i_386, intel_64 or amd_64 ? Yes, assuming you have COMPAT_FREEBSD32 in your kernel config (which GENERIC has, so most people have it). q:is it that the version labeled amd64 contains only 64_bit headers and source, which creates the 64_bit version of freebsd, as well as 64_bit versions of what i write, which will run as 64_bit code on the intel_64 and the amd_64, but, not the i_386 ? Yes. q:if a i386 version is installed on an intel_64 platform, then the pointers are 32_bits_wide, no matter what ? Yes. FreeBSD's models are ILP32 (int, long, pointer are all 32-bit) or LP64 (int is 32-bit, long and pointer are 64-bit). q:if i want to produce both 32_bit and 64_bit versions of my killer_app, then i need two machines, one a 32_bit or a 64_bit running i386, the other --only-- a 64_bit running amd64 ? Or an amd64 machine with a 32-bit world installed in a subdirectory that you can chroot to to do your 32-bit compiles, or a virtual machine running a 32-bit world. q:given that i have intel_64 hardware, do i need to start acquiring the amd64 versions of the releases, rather_than / in_addition_to the i386 versions ? If you have more than 4GB of ram, it would be a good idea. If you have 4GB or less, then 64-bit mode doesn't buy you much, and may cost you performance since all your pointers take up twice the space, filling up your L1/L2 caches twice as fast. q:given that --i-- am committed to 64_bit hardware, perhaps, i should give up on the i386 versions of the releases and require my users to spend us$_300 on 64_bit hardware [ it would save a large number of conditional_compilation directives; nudge_nudge, wink_wink, say no more ] ? Or provide source and let the users compile what they need on their own machines. Assuming you code using the appropriate types (size_t, intptr_t, etc, or int32_t and int64_t for when you know you need a particular word size) instead of assuming that a pointer will fit in an int, your code should compile on either 32- or 64-bit machines with no conditional code. http://www.opengroup.org/onlinepubs/9699919799/basedefs/stdint.h.html -- Dan Nelson dnel...@allantgroup.com ___ freebsd-questions@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-questions To unsubscribe, send any mail to freebsd-questions-unsubscr...@freebsd.org
