Messages in this thread | | | Subject | Re: [RESEND PATCH v5 5/5] Documentation/vmcoreinfo: Add documentation for 'TCR_EL1.T1SZ' | From | Bhupesh Sharma <> | Date | Thu, 26 Dec 2019 00:19:35 +0530 |
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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.
Thanks, Bhupesh
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