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From:   Arnd Bergmann <arnd@arndb.de>
Date:   Thu, 8 Jul 2021 15:23:59 +0200
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Subject: Re: [PATCH 10/19] LoongArch: Add signal handling support
To:     Huacai Chen <chenhuacai@gmail.com>
Cc:     Huacai Chen <chenhuacai@loongson.cn>,
        Andy Lutomirski <luto@kernel.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        Peter Zijlstra <peterz@infradead.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        David Airlie <airlied@linux.ie>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        linux-arch <linux-arch@vger.kernel.org>,
        Xuefeng Li <lixuefeng@loongson.cn>,
        Jiaxun Yang <jiaxun.yang@flygoat.com>,
        "Eric W. Biederman" <ebiederm@xmission.com>
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On Thu, Jul 8, 2021 at 3:04 PM Huacai Chen <chenhuacai@gmail.com> wrote:
> On Tue, Jul 6, 2021 at 6:17 PM Arnd Bergmann <arnd@arndb.de> wrote:
> > On Tue, Jul 6, 2021 at 6:18 AM Huacai Chen <chenhuacai@loongson.cn> wrote:
> > > +
> > > +#ifndef _NSIG
> > > +#define _NSIG          128
> > > +#endif
> >
> > Everything else uses 64 here, except for MIPS.
>
> Once before we also wanted to use 64, but we also want to use LBT to
> execute X86/MIPS/ARM binaries, so we chose the largest value (128).
> Some applications, such as sighold02 in LTP, will fail if _NSIG is not
> big enough.

Have you tried separating the in-kernel _NSIG from the number used
in the loongarch ABI? This may require a few changes to architecture
independent signal handling code, but I think it would be a cleaner
solution, and make it easier to port existing software without having
to special-case loongarch along with mips.

      Arnd