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Date:   Tue, 06 Jun 2023 16:08:34 -0700
From:   "H. Peter Anvin" <hpa@zytor.com>
To:     Thomas Gleixner <tglx@linutronix.de>,
        "Li, Xin3" <xin3.li@intel.com>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "x86@kernel.org" <x86@kernel.org>,
        "kvm@vger.kernel.org" <kvm@vger.kernel.org>
CC:     "mingo@redhat.com" <mingo@redhat.com>,
        "bp@alien8.de" <bp@alien8.de>,
        "dave.hansen@linux.intel.com" <dave.hansen@linux.intel.com>,
        "peterz@infradead.org" <peterz@infradead.org>,
        "andrew.cooper3@citrix.com" <andrew.cooper3@citrix.com>,
        "Christopherson,, Sean" <seanjc@google.com>,
        "pbonzini@redhat.com" <pbonzini@redhat.com>,
        "Shankar, Ravi V" <ravi.v.shankar@intel.com>,
        "jiangshanlai@gmail.com" <jiangshanlai@gmail.com>,
        "Kang, Shan" <shan.kang@intel.com>
Subject: RE: [PATCH v8 30/33] x86/fred: allow dynamic stack frame size
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On June 6, 2023 6:27:25 AM PDT, Thomas Gleixner <tglx@linutronix=2Ede> wrot=
e:
>On Tue, Jun 06 2023 at 06:18, Xin3 Li wrote:
>>> > A FRED stack frame could contain different amount of information for
>>> > This approach also works for IDT, thus we unify the code=2E
>>>=20
>>> And thereby remove the useful comment and replace it with an undocumen=
ted
>>> macro mess=2E
>>>=20
>>> I'm simply refusing to review this=2E It's not my job to understand th=
is
>>> undocumented hackery=2E
>>>=20
>>
>> I believe it's a nice idea to allow dynamic stack frame size, at least =
for
>> FRED=2E
>
>Believe belongs in the realm of religion=2E What we need here are proper
>facts, explanations and justifications=2E Nice ideas are not helpful when
>they are not having a value=2E
>
>> It's totally my bad that I didn't make it meet the minimum standards,
>> I will rewrite the commit message and add better comments=2E
>>
>> After a second thought, I probably should only apply the change to FRED=
 for
>> 2 reasons, the change seems problematic with ESPFIX (which FRED
>> doesn't need),
>
>Indeed=2E Making this FRED only is going to need even more justification=
=2E
>
>> and such corner cases are hard to test (self-tests needed?)
>
>There is a test=2E It's not that hard to find:
>
># git grep -li ESPFIX tools/testing/selftests/
>tools/testing/selftests/x86/sigreturn=2Ec
>
>Thanks,
>
>        tglx

For what it is worth, I am working on a FRED forward compatibly document a=
t the moment=2E