netdev - Re: [PATCH bpf-next 2/4] libbpf: fix libbpf build on compilers missing __builtin_mul

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Date:   Thu, 20 Aug 2020 07:21:12 -0700
From:   Yonghong Song <yhs@...com>
To:     Andrii Nakryiko <andriin@...com>, <bpf@...r.kernel.org>,
        <netdev@...r.kernel.org>, <ast@...com>, <daniel@...earbox.net>
CC:     <andrii.nakryiko@...il.com>, <kernel-team@...com>
Subject: Re: [PATCH bpf-next 2/4] libbpf: fix libbpf build on compilers
 missing __builtin_mul_overflow



On 8/19/20 11:14 PM, Andrii Nakryiko wrote:
> GCC compilers older than version 5 don't support __builtin_mul_overflow yet.
> Given GCC 4.9 is the minimal supported compiler for building kernel and the
> fact that libbpf is a dependency of resolve_btfids, which is dependency of
> CONFIG_DEBUG_INFO_BTF=y, this needs to be handled. This patch fixes the issue
> by falling back to slower detection of integer overflow in such cases.
> 
> Fixes: 029258d7b228 ("libbpf: Remove any use of reallocarray() in libbpf")
> Signed-off-by: Andrii Nakryiko <andriin@...com>

Acked-by: Yonghong Song <yhs@...com>