From: Bhupesh Sharma <bhsharma@redhat.com>
To: James Morse <james.morse@arm.com>, linux-kernel@vger.kernel.org
Cc: Mark Rutland <mark.rutland@arm.com>,
Ard Biesheuvel <ard.biesheuvel@linaro.org>,
linux-doc@vger.kernel.org, Will Deacon <will@kernel.org>,
x86@kernel.org, kexec@lists.infradead.org,
Kazuhito Hagio <k-hagio@ab.jp.nec.com>,
Dave Anderson <anderson@redhat.com>,
Catalin Marinas <catalin.marinas@arm.com>,
bhupesh.linux@gmail.com, linuxppc-dev@lists.ozlabs.org,
linux-arm-kernel@lists.infradead.org,
Steve Capper <steve.capper@arm.com>
Subject: Re: [RESEND PATCH v5 5/5] Documentation/vmcoreinfo: Add documentation for 'TCR_EL1.T1SZ'
Date: Thu, 26 Dec 2019 00:19:35 +0530 [thread overview]
Message-ID: <b7d8d603-d9fe-3e18-c754-baf2015acd16@redhat.com> (raw)
In-Reply-To: <8a982138-f1fa-34e8-18fd-49a79cea3652@arm.com>
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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next prev parent reply other threads:[~2019-12-25 18:50 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-11-29 19:59 [RESEND PATCH v5 0/5] Append new variables to vmcoreinfo (TCR_EL1.T1SZ for arm64 and MAX_PHYSMEM_BITS for all archs) Bhupesh Sharma
2019-11-29 19:59 ` [RESEND PATCH v5 1/5] crash_core, vmcoreinfo: Append 'MAX_PHYSMEM_BITS' to vmcoreinfo Bhupesh Sharma
2019-11-29 19:59 ` [RESEND PATCH v5 2/5] arm64/crash_core: Export TCR_EL1.T1SZ in vmcoreinfo Bhupesh Sharma
2019-12-12 10:32 ` James Morse
2019-12-25 19:01 ` Bhupesh Sharma
2020-01-10 18:39 ` James Morse
2020-01-10 19:00 ` Dave Anderson
2020-01-13 12:14 ` Bhupesh Sharma
2020-02-21 9:06 ` Amit Kachhap
2020-02-24 6:25 ` Bhupesh Sharma
2020-04-29 23:04 ` Scott Branden
2020-06-10 16:47 ` Bharat Gooty
2020-06-16 19:24 ` Bhupesh Sharma
2020-06-10 16:49 ` Bharat Gooty
2019-11-29 19:59 ` [RESEND PATCH v5 3/5] Documentation/arm64: Fix a simple typo in memory.rst Bhupesh Sharma
2019-11-29 19:59 ` [RESEND PATCH v5 4/5] Documentation/vmcoreinfo: Add documentation for 'MAX_PHYSMEM_BITS' Bhupesh Sharma
2019-11-29 19:59 ` [RESEND PATCH v5 5/5] Documentation/vmcoreinfo: Add documentation for 'TCR_EL1.T1SZ' Bhupesh Sharma
2019-12-12 10:32 ` James Morse
2019-12-25 18:49 ` Bhupesh Sharma [this message]
2020-06-03 18:47 ` Scott Branden
2020-06-03 20:38 ` Bhupesh Sharma
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