linux-kernel - Re: [PATCH v3 0/4] btf: support ints larger than 128 bits

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Message-ID: <20210105195113.lr3mc5ma2rvej4r6@kafai-mbp>
Date:   Tue, 5 Jan 2021 11:51:13 -0800
From:   Martin KaFai Lau <kafai@...com>
To:     Sean Young <sean@...s.org>
CC:     Yonghong Song <yhs@...com>, Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        Andrii Nakryiko <andrii@...nel.org>,
        Song Liu <songliubraving@...com>,
        John Fastabend <john.fastabend@...il.com>,
        KP Singh <kpsingh@...nel.org>,
        Nathan Chancellor <natechancellor@...il.com>,
        Nick Desaulniers <ndesaulniers@...gle.com>,
        Quentin Monnet <quentin@...valent.com>,
        Toke Høiland-Jørgensen <toke@...hat.com>,
        <linux-doc@...r.kernel.org>, <netdev@...r.kernel.org>,
        <bpf@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <clang-built-linux@...glegroups.com>
Subject: Re: [PATCH v3 0/4] btf: support ints larger than 128 bits

On Tue, Jan 05, 2021 at 02:45:30PM +0000, Sean Young wrote:
> clang supports arbitrary length ints using the _ExtInt extension. This
> can be useful to hold very large values, e.g. 256 bit or 512 bit types.
> 
> Larger types (e.g. 1024 bits) are possible but I am unaware of a use
> case for these.
> 
> This requires the _ExtInt extension enabled in clang, which is under
> review.
1. Please explain the use case.
2. All patches have the same commit message which is not useful.
   Please spend some time in the commit message to explain what each
   individual patch does.
3. The test_extint.py is mostly a copy-and-paste from the existing
   test_offload.py?  Does it need most of the test_offload.py
   to test the BTF 256/512 bit int?  Please create a minimal
   test and use the test_progs.c infra-structure.