From: Bhupesh Sharma <bhsharma@redhat.com>
To: James Morse <james.morse@arm.com>, linux-kernel@vger.kernel.org
Cc: bhupesh.linux@gmail.com, x86@kernel.org,
linuxppc-dev@lists.ozlabs.org,
linux-arm-kernel@lists.infradead.org, linux-doc@vger.kernel.org,
kexec@lists.infradead.org, Mark Rutland <mark.rutland@arm.com>,
Will Deacon <will@kernel.org>,
Steve Capper <steve.capper@arm.com>,
Catalin Marinas <catalin.marinas@arm.com>,
Ard Biesheuvel <ard.biesheuvel@linaro.org>,
Dave Anderson <anderson@redhat.com>,
Kazuhito Hagio <k-hagio@ab.jp.nec.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
next prev parent reply other threads:[~2019-12-25 18:49 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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