IO memory read from /proc/vmcore leads to hang.

[Maxim Uvarov]

Second kernel should already know that it's not system ram of the
first kernel and in that case makedumpfile will not dump that memory.
Simple way is to pass additional kernel argument to kexec is when you
load the kernel. If it works than you can think how it's better to
pass this parameter.  Variants might be request_resource() in first
kernel or add some logic to kexec tools.

Best regards,
Maxim.

2016-07-20 22:18 GMT+03:00 Daniel Walker <danielwa at cisco.com>:
>
> Mahesh, I didn't get your email for some reason . I saw it in the Archives.
>
> makedumpfile doesn't appear to have a way to drop free form memory areas. So
> I need to drop 00800000 to 00807fff , but I don't see a way to do that. Any
> other suggestions on how to prevent this hang ?
>
>
>
> On 07/11/2016 02:46 PM, Daniel Walker wrote:
>>
>>
>> Hi,
>>
>> I found found that on my Powerpc machine there is some IO memory which
>> will cause the box to hang if I read it. It's a custom device that was added
>> to the board for a special purpose.
>>
>> I was looking for a way to exclude this memory from the dump, and while
>> doing that I found that kexec makes a list of memory segments that go into
>> the core file. I was wondering why most of the kexec architecture don't
>> appear to exclude device memory like what's listed in /proc/iomem.
>>
>> Is there a good reason why that's not the case?
>>
>> Daniel
>
>
>
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-- 
Best regards,
Maxim Uvarov