Re: [Patch] min_low_pfn and max_low_pfn calcultion fix

[Jay Lan <jlan@sgi.com>]

Horms wrote:
> On Wed, Mar 14, 2007 at 11:48:15AM -0700, Jay Lan wrote:
>> Jay Lan wrote:
>>> Jay Lan wrote:
>>>> Magnus Damm wrote:
>>>> [snip]
>>>>>> I tested on 2.6.21-rc3 with DEBUG_VM turned on. The vanilla 2.6.21-rc3
>>>>>> without Nan-hai's patch, panicked on bugcheck on free_initmem->free_page
>>>>>> as predicted. We still need this patch.
>>>>> Ok, thanks for testing. =)
>>>>>
>>>>>> However, the zero-size vmcore problem is back on SN. But that is a
>>>>>> dfiffernet problem.
>>>>> Argh, more problems...
>>>> I found the problem. It was the "elfcorehdr" introduced in 2.6.21-rc1.
>>>> Without specifying it, the elfcorehdr_addr is initialized to
>>>> ELFCORE_ADDR_MAX. Later, a check in reserve_elfcorehdr will fail:
>>>>         if (elfcorehdr_addr >= ELFCORE_ADDR_MAX)
>>>>                 return -EINVAL;
>>>>
>>>> Is it supposed to be a physical address to store elf core header?
>>>> If so, it is not possible for SN to provide a physical address at
>>>> boot time, just like in the case of crashkernel=X@Y where Y is not used.
>>> Sorry, the elfcorehdr parameter is provided to the kdump kernel by
>>> kexec. The problem is in the reserve_elfcorehdr logic introduced in
>>> 2.6.21-rc1.
>>>
>>> When booting up the kdump kernel, i observed a failure in
>>> reserve_elfcorehdr. The below are my debugging messages:
>>>
>>> elfcorehdr_addr027fe4000, ELFCORE_ADDR_MAXÿffffffffffffff
>>> Cannot locate EFI vmcore descriptor
>>> reserve_elfcorehdr: vmcore descriptor size = 0
>>> reserve_memory: FAIL to reserve reserve_elfcorehdr
>> Hi Tony,
>>
>> The kernel code 2.6.21-rc3+ is fine wrt zero-size-vmcore issue.
>>
>> I have been testing on a rhel5 environment. The /sbin/kexec worked
>> for me up to 2.6.20.
>>
>> I then built a new kexec from tot kexec-tools-testing git tree and
>> i no longer see the zero-size-vmcore problem.
> 
> I take it that elfcorehdr is also correct in this environment?

Yes. I got a good vmcore.

Regards,
 - jay


> 
> The latest (ia64) kernels need a fairly recent kexec-tools-testing
> because of the change "kexec: Use EFI_LOADER_DATA for ELF core header".
> A recent kexec-tools-testing is probably needed for other reasons,
> though I can't think of them off-hand.
>