Saveoops: Making Kexec purgatory position-independent?
Ahmed S. Darwish
darwish.07 at gmail.com
Sat Feb 26 11:20:08 EST 2011
I'm continuing work on 'Saveoops', saving both early and normal Linux
oops log to disk upon panic [*], using Kexec and bootloaders this time.
Purgatory, the transitional mini-kernel used by kexec, is a relocatable
ELF file. Userspace kexec-tools finds the final load address of such
code (by parsing /proc/iomem, etc) and then applies the relocations
itself before passing the now-ready executable image to kernel.
Since capturing early oopses is the major goal, doing such relocation
in userspace won't fit my purposes. Two options remain:
- relocate purgatory entries in the kernel early boot path
- or compile purgatory as position-independent, thus simplifying
the kernel load logic
The former will add extra logic in a sensitive path (early boot), while
the latter will require changes inside the purgatory code itself,
especially i386 assembly files.
Any preferable option from our kexec and x86 maintainers?
More information about the kexec