kexec: Clearing registers just before jumping into purgatory

2013-10-11 Thread Daniel Kiper
Hi, Could you explain why do you clear all registers just before jumping into purgatory (please look into arch/x86/kernel/relocate_kernel_64.S for more details)? There is no any single word about that. I do not count comment which states what is going on. purgatory on entry does not assume any

[PATCH v2] makedumpfile: fix max_mapnr issue on system has over 44-bit addressing

2013-10-11 Thread Jingbai Ma
This patch will fix a bug of makedumpfile doesn't work correctly on system has over 44-bit addressing in compression dump mode. This bug was posted here: http://lists.infradead.org/pipermail/kexec/2013-September/009587.html This patch will add 3 new fields in struct kdump_sub_header. unsigned

[PATCH v2] crash utility: fix max_mapnr issue on system has over 44-bit addressing

2013-10-11 Thread Jingbai Ma
The patch will add support for new compressed dumpfile header_version 6. This bug was posted here: http://lists.infradead.org/pipermail/kexec/2013-September/009587.html This patch will add a new field in struct kdump_sub_header. unsigned long max_mapnr; And the old unsigned int max_mapnr in

Re: kexec: Clearing registers just before jumping into purgatory

2013-10-11 Thread Eric W. Biederman
Daniel Kiper daniel.ki...@oracle.com writes: Hi, Could you explain why do you clear all registers just before jumping into purgatory (please look into arch/x86/kernel/relocate_kernel_64.S for more details)? There is no any single word about that. I do not count comment which states what is

Re: kexec: Clearing registers just before jumping into purgatory

2013-10-11 Thread Daniel Kiper
On Fri, Oct 11, 2013 at 03:08:43AM -0700, ebied...@xmission.com wrote: Daniel Kiper daniel.ki...@oracle.com writes: Hi, Could you explain why do you clear all registers just before jumping into purgatory (please look into arch/x86/kernel/relocate_kernel_64.S for more details)? There is

Re: kexec: Clearing registers just before jumping into purgatory

2013-10-11 Thread Vivek Goyal
On Fri, Oct 11, 2013 at 01:04:55PM +0200, Daniel Kiper wrote: [..] In theory you can swap between to kernels with the preserve_context case. Technically I like the ability but I don't know that it has ever achieved much uptake. I think that this is nice idea too. However, I have not

Re: kexec: Clearing registers just before jumping into purgatory

2013-10-11 Thread Matthew Garrett
On Fri, Oct 11, 2013 at 08:52:06AM -0400, Vivek Goyal wrote: On Fri, Oct 11, 2013 at 01:04:55PM +0200, Daniel Kiper wrote: [..] In theory you can swap between to kernels with the preserve_context case. Technically I like the ability but I don't know that it has ever achieved much

Re: kexec: Clearing registers just before jumping into purgatory

2013-10-11 Thread Vivek Goyal
On Fri, Oct 11, 2013 at 04:37:27PM +0100, Matthew Garrett wrote: On Fri, Oct 11, 2013 at 08:52:06AM -0400, Vivek Goyal wrote: On Fri, Oct 11, 2013 at 01:04:55PM +0200, Daniel Kiper wrote: [..] In theory you can swap between to kernels with the preserve_context case. Technically I

Re: kexec: Clearing registers just before jumping into purgatory

2013-10-11 Thread Matthew Garrett
On Fri, Oct 11, 2013 at 11:44:50AM -0400, Vivek Goyal wrote: Just Curious. How is it useful. IOW, what's your use case of booting a new kernel and then jumping back. I'm kexecing into a kernel with a modified /dev/mem, modifying the original kernel and then jumping back into it. -- Matthew

Re: kexec: Clearing registers just before jumping into purgatory

2013-10-11 Thread Richard Weinberger
On Fri, Oct 11, 2013 at 5:48 PM, Matthew Garrett mj...@srcf.ucam.org wrote: On Fri, Oct 11, 2013 at 11:44:50AM -0400, Vivek Goyal wrote: Just Curious. How is it useful. IOW, what's your use case of booting a new kernel and then jumping back. I'm kexecing into a kernel with a modified

Re: kexec: Clearing registers just before jumping into purgatory

2013-10-11 Thread Matthew Garrett
On Fri, Oct 11, 2013 at 06:33:23PM +0200, Richard Weinberger wrote: On Fri, Oct 11, 2013 at 5:48 PM, Matthew Garrett mj...@srcf.ucam.org wrote: On Fri, Oct 11, 2013 at 11:44:50AM -0400, Vivek Goyal wrote: Just Curious. How is it useful. IOW, what's your use case of booting a new kernel

Re: kexec: Clearing registers just before jumping into purgatory

2013-10-11 Thread Richard Weinberger
On Fri, Oct 11, 2013 at 6:39 PM, Matthew Garrett mj...@srcf.ucam.org wrote: On Fri, Oct 11, 2013 at 06:33:23PM +0200, Richard Weinberger wrote: On Fri, Oct 11, 2013 at 5:48 PM, Matthew Garrett mj...@srcf.ucam.org wrote: On Fri, Oct 11, 2013 at 11:44:50AM -0400, Vivek Goyal wrote: Just

Re: kexec: Clearing registers just before jumping into purgatory

2013-10-11 Thread Matthew Garrett
On Fri, Oct 11, 2013 at 06:42:36PM +0200, Richard Weinberger wrote: On Fri, Oct 11, 2013 at 6:39 PM, Matthew Garrett mj...@srcf.ucam.org wrote: On Fri, Oct 11, 2013 at 06:33:23PM +0200, Richard Weinberger wrote: On Fri, Oct 11, 2013 at 5:48 PM, Matthew Garrett mj...@srcf.ucam.org wrote:

Re: kexec: Clearing registers just before jumping into purgatory

2013-10-11 Thread Richard Weinberger
Am 11.10.2013 18:44, schrieb Matthew Garrett: On Fri, Oct 11, 2013 at 06:42:36PM +0200, Richard Weinberger wrote: On Fri, Oct 11, 2013 at 6:39 PM, Matthew Garrett mj...@srcf.ucam.org wrote: On Fri, Oct 11, 2013 at 06:33:23PM +0200, Richard Weinberger wrote: On Fri, Oct 11, 2013 at 5:48 PM,

Re: kexec: Clearing registers just before jumping into purgatory

2013-10-11 Thread Vivek Goyal
On Fri, Oct 11, 2013 at 05:44:00PM +0100, Matthew Garrett wrote: On Fri, Oct 11, 2013 at 06:42:36PM +0200, Richard Weinberger wrote: On Fri, Oct 11, 2013 at 6:39 PM, Matthew Garrett mj...@srcf.ucam.org wrote: On Fri, Oct 11, 2013 at 06:33:23PM +0200, Richard Weinberger wrote: On Fri,

Re: kexec: Clearing registers just before jumping into purgatory

2013-10-11 Thread Matthew Garrett
On Fri, Oct 11, 2013 at 12:53:51PM -0400, Vivek Goyal wrote: On Fri, Oct 11, 2013 at 05:44:00PM +0100, Matthew Garrett wrote: I have /dev/mem and a list of addresses I want to modify. Why to boot in a second kernel to modify first kernel's RAM. Why not do it directly from the first kernel

Re: kexec: Clearing registers just before jumping into purgatory

2013-10-11 Thread Matthew Garrett
On Fri, Oct 11, 2013 at 06:47:19PM +0200, Richard Weinberger wrote: But you still need a magic tool which create you this list. I just read /proc/kallsyms. I'm really not doing anything complicated. If you have a tool which takes two kernel images and create such a delta, fine. Isn't that

Re: kexec: Clearing registers just before jumping into purgatory

2013-10-11 Thread Richard Weinberger
Am 11.10.2013 18:55, schrieb Matthew Garrett: On Fri, Oct 11, 2013 at 06:47:19PM +0200, Richard Weinberger wrote: But you still need a magic tool which create you this list. I just read /proc/kallsyms. I'm really not doing anything complicated. If you have a tool which takes two kernel

Re: kexec: Clearing registers just before jumping into purgatory

2013-10-11 Thread Matthew Garrett
On Fri, Oct 11, 2013 at 06:59:41PM +0200, Richard Weinberger wrote: Am 11.10.2013 18:55, schrieb Matthew Garrett: On Fri, Oct 11, 2013 at 06:47:19PM +0200, Richard Weinberger wrote: But you still need a magic tool which create you this list. I just read /proc/kallsyms. I'm really not

Re: [PATCH v2] crash utility: fix max_mapnr issue on system has over 44-bit addressing

2013-10-11 Thread Dave Anderson
Hello Jingbai, The old diskdump-compatibility issue has been addressed by this second patch, but it fails to work with split kdumps. I only have two sample split compressed kdumps. Despite the dumpfile names, both of them were compressed and filtered with -c -d31. Here is the first one: $

Re: kexec: Clearing registers just before jumping into purgatory

2013-10-11 Thread Eric W. Biederman
Matthew Garrett mj...@srcf.ucam.org writes: On Fri, Oct 11, 2013 at 06:59:41PM +0200, Richard Weinberger wrote: Am 11.10.2013 18:55, schrieb Matthew Garrett: On Fri, Oct 11, 2013 at 06:47:19PM +0200, Richard Weinberger wrote: But you still need a magic tool which create you this list.

Re: kexec: Clearing registers just before jumping into purgatory

2013-10-11 Thread Matthew Garrett
On Fri, Oct 11, 2013 at 01:44:19PM -0700, Eric W. Biederman wrote: Matthew Garrett mj...@srcf.ucam.org writes: No, I manually look up some addresses from /proc/kallsyms and then modify them in the second kernel. An interesting approach I think most of the rest of us would have just built

Re: kexec: Clearing registers just before jumping into purgatory

2013-10-11 Thread Eric W. Biederman
Daniel Kiper daniel.ki...@oracle.com writes: On Fri, Oct 11, 2013 at 03:08:43AM -0700, ebied...@xmission.com wrote: Daniel Kiper daniel.ki...@oracle.com writes: Hi, Could you explain why do you clear all registers just before jumping into purgatory (please look into

Re: [PATCH v2] crash utility: fix max_mapnr issue on system has over 44-bit addressing

2013-10-11 Thread Jingbai Ma
On 10/12/2013 02:52 AM, Dave Anderson wrote: Hello Jingbai, The old diskdump-compatibility issue has been addressed by this second patch, but it fails to work with split kdumps. I only have two sample split compressed kdumps. Despite the dumpfile names, both of them were compressed and