Messages in this thread | | | Date | Thu, 03 Feb 2005 16:28:10 +0900 | From | Itsuro Oda <> | Subject | Re: [Fastboot] [PATCH] Reserving backup region for kexec based crashdumps. |
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Hi,
On 02 Feb 2005 08:24:03 -0700 ebiederm@xmission.com (Eric W. Biederman) wrote: > > So the kernel+initrd that captures a crash dump will live and execute > in a reserved area of memory. It needs to know which memory regions > are valid, and it needs to know small things like the final register > state of each cpu.
Exactly.
Please let me clarify what you are going to. 1) standard kernel: reserve a small contigous area for a dump kernel (this is not changed as the current code) 2) standard kernel: export the information of valid physical memory regions. (/proc/iomem or /proc/cpumem etc.) 3) kexec (system call?): store the information of valid physical memory regions as ELF program header to the reserved area (mentioned 1)). 4) standard kernel: when a panic occur, append (ex.) the register information as ELF note after the memory information (if necessary). and jump new kernel 5) dump kernel: export all valid physical memory (and saved register information) to the user. (as /dev/oldmem /proc/vmcore ?)
Is this correct ? one question: how the dump kernel know the saved area of ELF headers ?
one more question: I don't understand what the 640K backup area is. Please let me know why it is necessary.
Thanks. -- Itsuro ODA <oda@valinux.co.jp>
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