linux-kernel - Re: [PATCH -next] modpost: move some defines to the file head

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Message-ID: <CAK7LNASc9vXvHiDRarbKXq-m-9r0wso2VydBFMfd4sCt0mA_8w@mail.gmail.com>
Date:   Fri, 21 Jul 2023 20:58:20 +0900
From:   Masahiro Yamada <masahiroy@...nel.org>
To:     Palmer Dabbelt <palmer@...osinc.com>
Cc:     wangkefeng.wang@...wei.com, mcgrof@...nel.org, nathan@...nel.org,
        ndesaulniers@...gle.com, nicolas@...sle.eu,
        linux-kbuild@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH -next] modpost: move some defines to the file head

On Thu, Jul 13, 2023 at 1:28 AM Palmer Dabbelt <palmer@...osinc.com> wrote:
>
> On Wed, 12 Jul 2023 08:55:23 PDT (-0700), masahiroy@...nel.org wrote:
> > +To: Luis Chamberlain, the commiter of the breakage
> >
> >
> >
> > On Wed, Jul 12, 2023 at 10:44 AM Kefeng Wang <wangkefeng.wang@...wei.com> wrote:
> >>
> >> with "module: Ignore RISC-V mapping symbols too", build error occurs,
> >>
> >> scripts/mod/modpost.c: In function ‘is_valid_name’:
> >> scripts/mod/modpost.c:1055:57: error: ‘EM_RISCV’ undeclared (first use in this function)
> >>   return !is_mapping_symbol(name, elf->hdr->e_machine == EM_RISCV);
> >>
> >> Fix it by moving the EM_RISCV to the file head, also some other
> >> defines in case of similar problem in the future.
> >
> >
> >
> > BTW, why is the flag 'is_riscv' needed?
> >
> >
> > All symbols starting with '$' look special to me.
> >
> >
> >
> > Why not like this?
> >
> >
> >        if (str[0] == '$')
> >                  return true;
> >
> >        return false;
>
> There's a bit of commentary in the v1
> <https://lore.kernel.org/all/20230707054007.32591-1-palmer@rivosinc.com/>,
> but essentially it's not necessary.  I just wanted to play things safe
> and avoid changing the mapping symbol detection elsewhere in order to
> deal with RISC-V.
>
> IIRC we decided $ was special in RISC-V because there were some other
> ports that behaved that way, but it wasn't universal.  If folks are OK
> treating $-prefixed symbols as special everywhere that's fine with me, I
> just wasn't sure what the right answer was.
>
> There's also some similar arch-specific-ness with the labels and such in
> here.

Hi Palmer,

I am not a toolchain expert, but my gut feeling is
that the code was safer than needed.


I'd like to remove the 'is_riscv' switch rather than
applying this patch.

Will you send a patch, or do you want me to do so?




--
Best Regards
Masahiro Yamada