Re: [RFC][PATCH 0/2 -mm] kexec based hibernation
On Mon, 2007-08-27 at 13:15 +, Pavel Machek wrote: > Hi! > > > >> > Does this make sense? > > >> > > >> Yes, this is a sensible optimization. But I think it may be better to > > >> make bootloader load kernel D directly into a specified memory location. > > >> For example, we can add a option to "kernel" command of grub. > > >> > > >> And, I think we can do more in bootloader. Such as we can prepare > > >> two > > > > > > Yes, that would be nice. > > > > > > It will mean quite a bit of work, but I guess it should be the long > > > term goal. Loading restore kernel directly from bootloader means: > > > > > > 1) it is fast -- no need to boot another kernel > > > > > > 2) it is "classical" way of doing things > > > > > > On the other hand, we loose flexibility that way: > > > > > > 1) it locks you onto one bootloader > > > > > > 2) you no longer have userland there to do uncompression, decryption, > > > etc.. > > > > True although for the uncompression and decryption those aren't exactly > > foreign > > requirements for bootloaders. > > Well, uncompression yes, but crypto? What is that, some kind of > trusted computing thingie? > > We do RSA for uswsusp, that may be a bit of problem for a bootloader, > but I'm glad bootloaders are bloated already :-). As far as I know, the grub 2.0 uses a modular implementation scheme. That is, every OS loader (Multi-boot, Linux, FreeBSD etc), partition table, file system is implemented as a module, and these modules can be statically linked into the final image. So I think the hibernation image loading can be implemented in grub 2.0 in a manageable way. :) Best Regards, Huang Ying - 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: [RFC][PATCH 0/2 -mm] kexec based hibernation
Hi! > >> > Does this make sense? > >> > >> Yes, this is a sensible optimization. But I think it may be better to > >> make bootloader load kernel D directly into a specified memory location. > >> For example, we can add a option to "kernel" command of grub. > >> > >> And, I think we can do more in bootloader. Such as we can prepare > >> two > > > > Yes, that would be nice. > > > > It will mean quite a bit of work, but I guess it should be the long > > term goal. Loading restore kernel directly from bootloader means: > > > > 1) it is fast -- no need to boot another kernel > > > > 2) it is "classical" way of doing things > > > > On the other hand, we loose flexibility that way: > > > > 1) it locks you onto one bootloader > > > > 2) you no longer have userland there to do uncompression, decryption, > > etc.. > > True although for the uncompression and decryption those aren't exactly > foreign > requirements for bootloaders. Well, uncompression yes, but crypto? What is that, some kind of trusted computing thingie? We do RSA for uswsusp, that may be a bit of problem for a bootloader, but I'm glad bootloaders are bloated already :-). -- (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html - 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: [RFC][PATCH 0/2 -mm] kexec based hibernation
Pavel Machek <[EMAIL PROTECTED]> writes: > Hi! > >> > Does this make sense? >> >> Yes, this is a sensible optimization. But I think it may be better to >> make bootloader load kernel D directly into a specified memory location. >> For example, we can add a option to "kernel" command of grub. >> >> And, I think we can do more in bootloader. Such as we can prepare >> two > > Yes, that would be nice. > > It will mean quite a bit of work, but I guess it should be the long > term goal. Loading restore kernel directly from bootloader means: > > 1) it is fast -- no need to boot another kernel > > 2) it is "classical" way of doing things > > On the other hand, we loose flexibility that way: > > 1) it locks you onto one bootloader > > 2) you no longer have userland there to do uncompression, decryption, > etc.. True although for the uncompression and decryption those aren't exactly foreign requirements for bootloaders. Eric - 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: [RFC][PATCH 0/2 -mm] kexec based hibernation
Hi! > > Does this make sense? > > Yes, this is a sensible optimization. But I think it may be better to > make bootloader load kernel D directly into a specified memory location. > For example, we can add a option to "kernel" command of grub. > > And, I think we can do more in bootloader. Such as we can prepare > two Yes, that would be nice. It will mean quite a bit of work, but I guess it should be the long term goal. Loading restore kernel directly from bootloader means: 1) it is fast -- no need to boot another kernel 2) it is "classical" way of doing things On the other hand, we loose flexibility that way: 1) it locks you onto one bootloader 2) you no longer have userland there to do uncompression, decryption, etc.. Pave -- (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html - 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: [RFC][PATCH 0/2 -mm] kexec based hibernation
On Mon, Aug 27, 2007 at 02:18:49PM +0800, Huang, Ying wrote: [..] > > > > If one compiles the kernel C to boot from reserved memory area (subset > > of memory area used by kernel B), then I can skip the step of kexecing > > from C to D? (COFIG_PHYSICAL_START) > > Yes. I think so. > > > Alternatively, can we give hint to kernel C to run from a specified address > > at run time with the help of command line parameters. What I mean > > boot-loader > > can load the kernel at any address, but kernel will move itself to run > > from a different location depending on command line parameter. For example, > > let say kernel_run_addr = 0x100. This parameter will tell the kernel > > to move itself to 16MB address and run from there. I think it can be made > > to work with little work in existing setup of relocatable kernel. > > > > Kernel run address can be put by some user space script which will save > > the hibernated image of original kernel. So after saving the /proc/vmcore, > > script can modify the boot loader config file to append the right > > command line to the kernel (kernel_run_addr). > > > > After hibernation, user will shutdown/reboot. Next time the kernel boots > > it will load at 16MB addr (because of kernel_run_addr) and then it can > > restore the previously saved image. > > > > We shall have to get rid of (kernel_run_addr) parameter from command > > line while resuming. One can restore the image (krestore) and then edit > > the boot loader config file to get rid of command line param, > > kernel_run_addr. > > > > In this scheme, with the help of relocatable kernel, we can use a single > > kernel for everything. (A, B, C, D). We will also avoid additional kexec > > from kernel C to kernel D. > > > > I think in the long run we shall have to work out so that a user does > > not have to maintain multiple kernels. > > Only one relocatable kernel image is needed. In fact, I use one > relocatable kernel image in testing during development. > > > Does this make sense? > > Yes, this is a sensible optimization. But I think it may be better to > make bootloader load kernel D directly into a specified memory location. > For example, we can add a option to "kernel" command of grub. > IIUC, you mean a command line option which is parsed by boot-loader and then boot-loader loads the kernel at user specified address? I think it might not be a very good idea as hibernation becomes boot-loader dependent scheme. How many boot-loaders will one modify and hibernation will not work with older versions of boot-loader. I think it is better to make kernel relocate to user specified address and keep hibernation mechanism independent of specific boot-loader(grup, lilo,...) and boot-loader version. Thanks Vivek - 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: [RFC][PATCH 0/2 -mm] kexec based hibernation
On Mon, 2007-08-27 at 10:30 +0530, Vivek Goyal wrote: > On Mon, Aug 27, 2007 at 09:14:05AM +0800, Huang, Ying wrote: > > Kexec base hibernation has some potential advantages over uswsusp and > > TuxOnIce (suspend2). Some most obvious advantages are: > > > > 1. The hibernation image size can exceed half of memory size easily. > > > > 2. The hibernation image can be written to and read from almost > >anywhere, such as USB disk, NFS. > > > > 3. It is possible to eliminate freezer from kexec based hibernation > >implementation. > > > > 4. Based on kexec/kdump implementation, the kernel code needed is > >less. > > > > > > This patch set implements a prototype of kexec based hibernation. The > > kernel functionalities added are as follow: > > > > 1. Jumping from kexeced kernel back to original kernel. This is used > >by hibernation to save/load necessary state in original kernel and > >jumping back to original kernel after restore the memory of > >original kernel. > > > > 2. Add writing support to /dev/oldmem. This is used by hibernation to > >restore the memory of original kernel. > > > > > > The hibernation process with the patch set is as follow: > > > > 1. Boot a kernel A > > > > 2. Work under kernel A > > > > 3. Kexec another kernel B (crash dump enabled) in kernel A. > > > > 4. Save the memory image of kernel A through crash dump (such as "cp > >/proc/vmcore ~"). Save the "jump buffer pfn". > > > > 5. Shutdown or reboot > > > > > > The restore process with the patch set is as follow: > > > > 1. Boot a kernel C > > > > 2. Kexec another kernel D (crash dump enabled) in kernel C. The memory > >area used by kernel D must be a subset of memory area used by > >kernel B. > > > > If one compiles the kernel C to boot from reserved memory area (subset > of memory area used by kernel B), then I can skip the step of kexecing > from C to D? (COFIG_PHYSICAL_START) Yes. I think so. > Alternatively, can we give hint to kernel C to run from a specified address > at run time with the help of command line parameters. What I mean boot-loader > can load the kernel at any address, but kernel will move itself to run > from a different location depending on command line parameter. For example, > let say kernel_run_addr = 0x100. This parameter will tell the kernel > to move itself to 16MB address and run from there. I think it can be made > to work with little work in existing setup of relocatable kernel. > > Kernel run address can be put by some user space script which will save > the hibernated image of original kernel. So after saving the /proc/vmcore, > script can modify the boot loader config file to append the right > command line to the kernel (kernel_run_addr). > > After hibernation, user will shutdown/reboot. Next time the kernel boots > it will load at 16MB addr (because of kernel_run_addr) and then it can > restore the previously saved image. > > We shall have to get rid of (kernel_run_addr) parameter from command > line while resuming. One can restore the image (krestore) and then edit > the boot loader config file to get rid of command line param, kernel_run_addr. > > In this scheme, with the help of relocatable kernel, we can use a single > kernel for everything. (A, B, C, D). We will also avoid additional kexec > from kernel C to kernel D. > > I think in the long run we shall have to work out so that a user does > not have to maintain multiple kernels. Only one relocatable kernel image is needed. In fact, I use one relocatable kernel image in testing during development. > Does this make sense? Yes, this is a sensible optimization. But I think it may be better to make bootloader load kernel D directly into a specified memory location. For example, we can add a option to "kernel" command of grub. And, I think we can do more in bootloader. Such as we can prepare two kernel command line for one grub menu item, one for normal kernel, the other for restore kernel. After hibernating successfully, the effective kernel command line is switched. Best Regards, Huang Ying - 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: [RFC][PATCH 0/2 -mm] kexec based hibernation
On Mon, 2007-08-27 at 10:30 +0530, Vivek Goyal wrote: On Mon, Aug 27, 2007 at 09:14:05AM +0800, Huang, Ying wrote: Kexec base hibernation has some potential advantages over uswsusp and TuxOnIce (suspend2). Some most obvious advantages are: 1. The hibernation image size can exceed half of memory size easily. 2. The hibernation image can be written to and read from almost anywhere, such as USB disk, NFS. 3. It is possible to eliminate freezer from kexec based hibernation implementation. 4. Based on kexec/kdump implementation, the kernel code needed is less. This patch set implements a prototype of kexec based hibernation. The kernel functionalities added are as follow: 1. Jumping from kexeced kernel back to original kernel. This is used by hibernation to save/load necessary state in original kernel and jumping back to original kernel after restore the memory of original kernel. 2. Add writing support to /dev/oldmem. This is used by hibernation to restore the memory of original kernel. The hibernation process with the patch set is as follow: 1. Boot a kernel A 2. Work under kernel A 3. Kexec another kernel B (crash dump enabled) in kernel A. 4. Save the memory image of kernel A through crash dump (such as cp /proc/vmcore ~). Save the jump buffer pfn. 5. Shutdown or reboot The restore process with the patch set is as follow: 1. Boot a kernel C 2. Kexec another kernel D (crash dump enabled) in kernel C. The memory area used by kernel D must be a subset of memory area used by kernel B. If one compiles the kernel C to boot from reserved memory area (subset of memory area used by kernel B), then I can skip the step of kexecing from C to D? (COFIG_PHYSICAL_START) Yes. I think so. Alternatively, can we give hint to kernel C to run from a specified address at run time with the help of command line parameters. What I mean boot-loader can load the kernel at any address, but kernel will move itself to run from a different location depending on command line parameter. For example, let say kernel_run_addr = 0x100. This parameter will tell the kernel to move itself to 16MB address and run from there. I think it can be made to work with little work in existing setup of relocatable kernel. Kernel run address can be put by some user space script which will save the hibernated image of original kernel. So after saving the /proc/vmcore, script can modify the boot loader config file to append the right command line to the kernel (kernel_run_addr). After hibernation, user will shutdown/reboot. Next time the kernel boots it will load at 16MB addr (because of kernel_run_addr) and then it can restore the previously saved image. We shall have to get rid of (kernel_run_addr) parameter from command line while resuming. One can restore the image (krestore) and then edit the boot loader config file to get rid of command line param, kernel_run_addr. In this scheme, with the help of relocatable kernel, we can use a single kernel for everything. (A, B, C, D). We will also avoid additional kexec from kernel C to kernel D. I think in the long run we shall have to work out so that a user does not have to maintain multiple kernels. Only one relocatable kernel image is needed. In fact, I use one relocatable kernel image in testing during development. Does this make sense? Yes, this is a sensible optimization. But I think it may be better to make bootloader load kernel D directly into a specified memory location. For example, we can add a option to kernel command of grub. And, I think we can do more in bootloader. Such as we can prepare two kernel command line for one grub menu item, one for normal kernel, the other for restore kernel. After hibernating successfully, the effective kernel command line is switched. Best Regards, Huang Ying - 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: [RFC][PATCH 0/2 -mm] kexec based hibernation
On Mon, Aug 27, 2007 at 02:18:49PM +0800, Huang, Ying wrote: [..] If one compiles the kernel C to boot from reserved memory area (subset of memory area used by kernel B), then I can skip the step of kexecing from C to D? (COFIG_PHYSICAL_START) Yes. I think so. Alternatively, can we give hint to kernel C to run from a specified address at run time with the help of command line parameters. What I mean boot-loader can load the kernel at any address, but kernel will move itself to run from a different location depending on command line parameter. For example, let say kernel_run_addr = 0x100. This parameter will tell the kernel to move itself to 16MB address and run from there. I think it can be made to work with little work in existing setup of relocatable kernel. Kernel run address can be put by some user space script which will save the hibernated image of original kernel. So after saving the /proc/vmcore, script can modify the boot loader config file to append the right command line to the kernel (kernel_run_addr). After hibernation, user will shutdown/reboot. Next time the kernel boots it will load at 16MB addr (because of kernel_run_addr) and then it can restore the previously saved image. We shall have to get rid of (kernel_run_addr) parameter from command line while resuming. One can restore the image (krestore) and then edit the boot loader config file to get rid of command line param, kernel_run_addr. In this scheme, with the help of relocatable kernel, we can use a single kernel for everything. (A, B, C, D). We will also avoid additional kexec from kernel C to kernel D. I think in the long run we shall have to work out so that a user does not have to maintain multiple kernels. Only one relocatable kernel image is needed. In fact, I use one relocatable kernel image in testing during development. Does this make sense? Yes, this is a sensible optimization. But I think it may be better to make bootloader load kernel D directly into a specified memory location. For example, we can add a option to kernel command of grub. IIUC, you mean a command line option which is parsed by boot-loader and then boot-loader loads the kernel at user specified address? I think it might not be a very good idea as hibernation becomes boot-loader dependent scheme. How many boot-loaders will one modify and hibernation will not work with older versions of boot-loader. I think it is better to make kernel relocate to user specified address and keep hibernation mechanism independent of specific boot-loader(grup, lilo,...) and boot-loader version. Thanks Vivek - 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: [RFC][PATCH 0/2 -mm] kexec based hibernation
Hi! Does this make sense? Yes, this is a sensible optimization. But I think it may be better to make bootloader load kernel D directly into a specified memory location. For example, we can add a option to kernel command of grub. And, I think we can do more in bootloader. Such as we can prepare two Yes, that would be nice. It will mean quite a bit of work, but I guess it should be the long term goal. Loading restore kernel directly from bootloader means: 1) it is fast -- no need to boot another kernel 2) it is classical way of doing things On the other hand, we loose flexibility that way: 1) it locks you onto one bootloader 2) you no longer have userland there to do uncompression, decryption, etc.. Pave -- (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html - 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: [RFC][PATCH 0/2 -mm] kexec based hibernation
Pavel Machek [EMAIL PROTECTED] writes: Hi! Does this make sense? Yes, this is a sensible optimization. But I think it may be better to make bootloader load kernel D directly into a specified memory location. For example, we can add a option to kernel command of grub. And, I think we can do more in bootloader. Such as we can prepare two Yes, that would be nice. It will mean quite a bit of work, but I guess it should be the long term goal. Loading restore kernel directly from bootloader means: 1) it is fast -- no need to boot another kernel 2) it is classical way of doing things On the other hand, we loose flexibility that way: 1) it locks you onto one bootloader 2) you no longer have userland there to do uncompression, decryption, etc.. True although for the uncompression and decryption those aren't exactly foreign requirements for bootloaders. Eric - 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: [RFC][PATCH 0/2 -mm] kexec based hibernation
Hi! Does this make sense? Yes, this is a sensible optimization. But I think it may be better to make bootloader load kernel D directly into a specified memory location. For example, we can add a option to kernel command of grub. And, I think we can do more in bootloader. Such as we can prepare two Yes, that would be nice. It will mean quite a bit of work, but I guess it should be the long term goal. Loading restore kernel directly from bootloader means: 1) it is fast -- no need to boot another kernel 2) it is classical way of doing things On the other hand, we loose flexibility that way: 1) it locks you onto one bootloader 2) you no longer have userland there to do uncompression, decryption, etc.. True although for the uncompression and decryption those aren't exactly foreign requirements for bootloaders. Well, uncompression yes, but crypto? What is that, some kind of trusted computing thingie? We do RSA for uswsusp, that may be a bit of problem for a bootloader, but I'm glad bootloaders are bloated already :-). -- (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html - 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: [RFC][PATCH 0/2 -mm] kexec based hibernation
On Mon, 2007-08-27 at 13:15 +, Pavel Machek wrote: Hi! Does this make sense? Yes, this is a sensible optimization. But I think it may be better to make bootloader load kernel D directly into a specified memory location. For example, we can add a option to kernel command of grub. And, I think we can do more in bootloader. Such as we can prepare two Yes, that would be nice. It will mean quite a bit of work, but I guess it should be the long term goal. Loading restore kernel directly from bootloader means: 1) it is fast -- no need to boot another kernel 2) it is classical way of doing things On the other hand, we loose flexibility that way: 1) it locks you onto one bootloader 2) you no longer have userland there to do uncompression, decryption, etc.. True although for the uncompression and decryption those aren't exactly foreign requirements for bootloaders. Well, uncompression yes, but crypto? What is that, some kind of trusted computing thingie? We do RSA for uswsusp, that may be a bit of problem for a bootloader, but I'm glad bootloaders are bloated already :-). As far as I know, the grub 2.0 uses a modular implementation scheme. That is, every OS loader (Multi-boot, Linux, FreeBSD etc), partition table, file system is implemented as a module, and these modules can be statically linked into the final image. So I think the hibernation image loading can be implemented in grub 2.0 in a manageable way. :) Best Regards, Huang Ying - 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: [RFC][PATCH 0/2 -mm] kexec based hibernation
On Mon, Aug 27, 2007 at 09:14:05AM +0800, Huang, Ying wrote: > Kexec base hibernation has some potential advantages over uswsusp and > TuxOnIce (suspend2). Some most obvious advantages are: > > 1. The hibernation image size can exceed half of memory size easily. > > 2. The hibernation image can be written to and read from almost >anywhere, such as USB disk, NFS. > > 3. It is possible to eliminate freezer from kexec based hibernation >implementation. > > 4. Based on kexec/kdump implementation, the kernel code needed is >less. > > > This patch set implements a prototype of kexec based hibernation. The > kernel functionalities added are as follow: > > 1. Jumping from kexeced kernel back to original kernel. This is used >by hibernation to save/load necessary state in original kernel and >jumping back to original kernel after restore the memory of >original kernel. > > 2. Add writing support to /dev/oldmem. This is used by hibernation to >restore the memory of original kernel. > > > The hibernation process with the patch set is as follow: > > 1. Boot a kernel A > > 2. Work under kernel A > > 3. Kexec another kernel B (crash dump enabled) in kernel A. > > 4. Save the memory image of kernel A through crash dump (such as "cp >/proc/vmcore ~"). Save the "jump buffer pfn". > > 5. Shutdown or reboot > > > The restore process with the patch set is as follow: > > 1. Boot a kernel C > > 2. Kexec another kernel D (crash dump enabled) in kernel C. The memory >area used by kernel D must be a subset of memory area used by >kernel B. > If one compiles the kernel C to boot from reserved memory area (subset of memory area used by kernel B), then I can skip the step of kexecing from C to D? (COFIG_PHYSICAL_START) Alternatively, can we give hint to kernel C to run from a specified address at run time with the help of command line parameters. What I mean boot-loader can load the kernel at any address, but kernel will move itself to run from a different location depending on command line parameter. For example, let say kernel_run_addr = 0x100. This parameter will tell the kernel to move itself to 16MB address and run from there. I think it can be made to work with little work in existing setup of relocatable kernel. Kernel run address can be put by some user space script which will save the hibernated image of original kernel. So after saving the /proc/vmcore, script can modify the boot loader config file to append the right command line to the kernel (kernel_run_addr). After hibernation, user will shutdown/reboot. Next time the kernel boots it will load at 16MB addr (because of kernel_run_addr) and then it can restore the previously saved image. We shall have to get rid of (kernel_run_addr) parameter from command line while resuming. One can restore the image (krestore) and then edit the boot loader config file to get rid of command line param, kernel_run_addr. In this scheme, with the help of relocatable kernel, we can use a single kernel for everything. (A, B, C, D). We will also avoid additional kexec from kernel C to kernel D. I think in the long run we shall have to work out so that a user does not have to maintain multiple kernels. Does this make sense? Thanks Vivek - 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: [RFC][PATCH 0/2 -mm] kexec based hibernation
On Mon, Aug 27, 2007 at 09:14:05AM +0800, Huang, Ying wrote: Kexec base hibernation has some potential advantages over uswsusp and TuxOnIce (suspend2). Some most obvious advantages are: 1. The hibernation image size can exceed half of memory size easily. 2. The hibernation image can be written to and read from almost anywhere, such as USB disk, NFS. 3. It is possible to eliminate freezer from kexec based hibernation implementation. 4. Based on kexec/kdump implementation, the kernel code needed is less. This patch set implements a prototype of kexec based hibernation. The kernel functionalities added are as follow: 1. Jumping from kexeced kernel back to original kernel. This is used by hibernation to save/load necessary state in original kernel and jumping back to original kernel after restore the memory of original kernel. 2. Add writing support to /dev/oldmem. This is used by hibernation to restore the memory of original kernel. The hibernation process with the patch set is as follow: 1. Boot a kernel A 2. Work under kernel A 3. Kexec another kernel B (crash dump enabled) in kernel A. 4. Save the memory image of kernel A through crash dump (such as cp /proc/vmcore ~). Save the jump buffer pfn. 5. Shutdown or reboot The restore process with the patch set is as follow: 1. Boot a kernel C 2. Kexec another kernel D (crash dump enabled) in kernel C. The memory area used by kernel D must be a subset of memory area used by kernel B. If one compiles the kernel C to boot from reserved memory area (subset of memory area used by kernel B), then I can skip the step of kexecing from C to D? (COFIG_PHYSICAL_START) Alternatively, can we give hint to kernel C to run from a specified address at run time with the help of command line parameters. What I mean boot-loader can load the kernel at any address, but kernel will move itself to run from a different location depending on command line parameter. For example, let say kernel_run_addr = 0x100. This parameter will tell the kernel to move itself to 16MB address and run from there. I think it can be made to work with little work in existing setup of relocatable kernel. Kernel run address can be put by some user space script which will save the hibernated image of original kernel. So after saving the /proc/vmcore, script can modify the boot loader config file to append the right command line to the kernel (kernel_run_addr). After hibernation, user will shutdown/reboot. Next time the kernel boots it will load at 16MB addr (because of kernel_run_addr) and then it can restore the previously saved image. We shall have to get rid of (kernel_run_addr) parameter from command line while resuming. One can restore the image (krestore) and then edit the boot loader config file to get rid of command line param, kernel_run_addr. In this scheme, with the help of relocatable kernel, we can use a single kernel for everything. (A, B, C, D). We will also avoid additional kexec from kernel C to kernel D. I think in the long run we shall have to work out so that a user does not have to maintain multiple kernels. Does this make sense? Thanks Vivek - 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/
