Re: [Crash-utility] [Patch 1/4][kernel][slimdump] Add new elf-note of type NT_NOCOREDUMP to capture slimdump
On Wed, Oct 05, 2011 at 01:11:16PM +0530, K.Prasad wrote:
[..]
> Again, note_name and desc_msg seem to be only two exports.
Frankly desc
> string seems pretty obivious and we should be able to ignore it. So just
> exporting PANIC_MCE=true or something like that in case of MCE.
>
Yes, adding a new field to the VMCOREINFO note would have been much
simpler but there's a second part to the kdump + fatal MCE problem which
will need a new elf-note to solve.
On a system containing 'poisoned' pages (generated as a result of
detecting UC errors which haven't been 'consumed'), if a software bug
results
in crashing the machine, the ensuing kdump operation will read from the
faulty memory location. This will trigger a new crash within the context
of the kexec'ed kernel and we want to avoid this.
I think in other mail you mentioned that it is not known what happens
if we try to read pages marked as "poisoned".
The plan is to pass-down the list of poisoned memory pages to the second
kernel using an elf-note so that these pages are left untouched during
dump capture. I'm working on an implementation of the same and should
have patches soon.
I would say let us first figure out what happens while reading a poisoned
page and is this a problem before working on a solution.
Thanks
Vivek