Re: Re: [RESEND PATCH v5 5/5] Documentation/vmcoreinfo: Add documentation for 'TCR_EL1.T1SZ'

Scott Branden
2020-06-03T18:47:37Z

Hi Bhupesh,

Would be great to get this patch series upstreamed?

On 2019-12-25 10:49 a.m., Bhupesh Sharma wrote:
> Hi James,
>
> On 12/12/2019 04:02 PM, James Morse wrote:
>> Hi Bhupesh,
>
> I am sorry this review mail skipped my attention due to holidays and
> focus on other urgent issues.
>
>> On 29/11/2019 19:59, Bhupesh Sharma wrote:
>>> Add documentation for TCR_EL1.T1SZ variable being added to
>>> vmcoreinfo.
>>>
>>> It indicates the size offset of the memory region addressed by
>>> TTBR1_EL1
>>
>>> and hence can be used for determining the vabits_actual value.
>>
>> used for determining random-internal-kernel-variable, that might not
>> exist tomorrow.
>>
>> Could you describe how this is useful/necessary if a debugger wants
>> to walk the page
>> tables from the core file? I think this is a better argument.
>>
>> Wouldn't the documentation be better as part of the patch that adds
>> the export?
>> (... unless these have to go via different trees? ..)
>
> Ok, will fix the same in v6 version.
>
>>> diff --git a/Documentation/admin-guide/kdump/vmcoreinfo.rst
>>> b/Documentation/admin-guide/kdump/vmcoreinfo.rst
>>> index 447b64314f56..f9349f9d3345 100644
>>> --- a/Documentation/admin-guide/kdump/vmcoreinfo.rst
>>> +++ b/Documentation/admin-guide/kdump/vmcoreinfo.rst
>>> @@ -398,6 +398,12 @@ KERNELOFFSET
>>>   The kernel randomization offset. Used to compute the page offset. If
>>>   KASLR is disabled, this value is zero.
>>>   +TCR_EL1.T1SZ
>>> +------------
>>> +
>>> +Indicates the size offset of the memory region addressed by TTBR1_EL1
>>
>>> +and hence can be used for determining the vabits_actual value.
>>
>> 'vabits_actual' may not exist when the next person comes to read this
>> documentation (its
>> going to rot really quickly).
>>
>> I think the first half of this text is enough to say what this is
>> for. You should include
>> words to the effect that its the hardware value that goes with
>> swapper_pg_dir. You may
>> want to point readers to the arm-arm for more details on what the
>> value means.
>
> Ok, got it. Fixed this in v6, which should be on its way shortly.
I can't seem to find v6?
>
> Thanks,
> Bhupesh
>
>
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