Re: [RFC Patch 1/2] kexec: show memory info in /proc/iomem

Eric W. Biederman
2009-08-12T01:51:52Z

Amerigo Wang <amwang@redhat.com> writes:

>> Nacked-by: "Eric W. Biederman" <ebiederm@xmission.com>
>>
>> We can inspect the image we are going to load to get this information.
>> In fact /sbin/kexec already inspects the image we are going to load
>> to get this information. Putting this in the kernel adds kernel
>> complexity for no gain.
>>
>
> /sbin/kexec is supported to know this, of course. But this is not for
> /sbin/kexec, this is for user (or other programs) to observe the memory
> information, so that he can know the memory he reserved is too much or not.

> Without this, it is a little hard to use patch 2/2.

So add on option to /sbin/kexec.

Furthermore none of this does a good job of predicting how much
memory /sbin/fsck will require to check the filesystem before we
write a crash dump.

The only way I know of reliably obtaining that kind of information is
testing your crash userspace with different amounts of memory and
understanding what is going on.

Eric