[PATCH] Reserve memory for kdump kernel within RMO region
bernhard at bwalle.de
Thu Nov 26 14:26:44 EST 2009
M. Mohan Kumar schrieb:
> On 11/26/2009 12:22 AM, Bernhard Walle wrote:
>> M. Mohan Kumar schrieb:
>>> Reserve memory for kdump kernel within RMO region
>>> When the kernel size exceeds 32MB(observed with some distros), memory
>>> for kdump kernel can not be reserved as kdump kernel base is assumed to
>>> be 32MB always. When the kernel has CONFIG_RELOCATABLE option enabled,
>>> provide the feature to reserve the memory for kdump kernel anywhere in
>>> the RMO region.
> Hi Bernhard,
>> Correct me if I'm wrong, but: CONFIG_RELOCATABLE is for the kernel that
>> gets loaded as crashkernel, not for the kernel that loads the
>> crashkernel. So it would be perfectly fine that a kernel that has not
>> CONFIG_RELOCATABLE set would load another kernel that has
>> CONFIG_RELOCATABLE set on an address != 32 M.
> No, with relocatable option, the same kernel is used as both production
> and kdump kernel.
Can be, but it's not strictly necessary. It depends what userland does.
Especially it's possible that a non-relocatable, self-compiled kernel
loads a relocatable distribution kernel as capture kernel.
Also, it would make sense to make the behaviour symmetric across
platforms. Currently we have:
- x86 and ia64: Without offset on command line, use any offset
With offset on command line, use that offset and fail
if no memory is available at that offset.
- ppc64: Always use 32M and ignore the offset.
If your patch gets applied, we have:
- ppc64: With CONFIG_RELOCATABLE, use any offset
With offset on command
I don't see why the behaviour on ppc64 should be completely different.
Having maintained kdump for SUSE for x86, ia64 and partly ppc64 in the
past, I always felt that ppc64 is more different from x86 than ia64 is
from x86. That's one more step into that direction without a technical
Having that all said: If your patch gets in mainline kernel, than we
should change the behaviour also for x86 and ia64.
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