From: Masahiro Yamada <masahiroy@kernel.org>
To: Bagas Sanjaya <bagasdotme@gmail.com>
Cc: Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Linux Kernel Build System <linux-kbuild@vger.kernel.org>,
Sami Tolvanen <samitolvanen@google.com>,
Kees Cook <keescook@chromium.org>, Xu Zhen <xuzhen@fastmail.com>,
Nathan Chancellor <nathan@kernel.org>
Subject: Re: Incorrect thinlto cache directory path in Makefile
Date: Sun, 12 May 2024 22:14:40 +0900 [thread overview]
Message-ID: <CAK7LNASVN7he-iuSTY8Z2cvxRA=97iqZHbW3mNL_38xzdbcvyw@mail.gmail.com> (raw)
In-Reply-To: <CAK7LNARrG0u2pSzAkdbzrcf_i7ByhEnDwHH=4LtaE_H7OgL=0A@mail.gmail.com>
On Sun, May 12, 2024 at 10:04 PM Masahiro Yamada <masahiroy@kernel.org> wrote:
>
> +CC: Nathan
>
>
> On Sat, May 11, 2024 at 8:18 PM Bagas Sanjaya <bagasdotme@gmail.com> wrote:
> >
> > Hi,
> >
> > Xu Zhen <xuzhen@fastmail.com> reported on Bugzilla (https://bugzilla.kernel.org/show_bug.cgi?id=218825) thinlto build directory problem (especially on
> > DKMS modules). He wrote:
> >
> > > In Makefile, the ld flag `--thinlto-cache-dir' is set to
> > > `$(extmod_prefix).thinlto-cache'. But at that time, the variable extmod_prefix
> > > had not been assigned yet. Therefore, the thinlto cache dir is always created
> > > in the current directory.
> > >
> > > Even worse, the cache dir cannot be deleted when executing `make clean'. This
> > > is because its path was written as `$(KBUILD_EXTMOD)/.thinlto-cache' in the
> > > clean: target.
> > >
> > > Some users have been troubled by it: https://github.com/dell/dkms/issues/292
> > >
> > > This bug was introduced by commit dc5723b02e523b2c4a68667f7e28c65018f7202f
>
>
> I agree this is a bug.
>
>
>
>
> line 945:
> KBUILD_LDFLAGS += --thinlto-cache-dir=$(extmod_prefix).thinlto-cache
>
>
> line 1034:
> KBUILD_LDFLAGS += $(call ld-option,--no-warn-rwx-segments)
This one is probably OK because it is guarded by CONFIG_LD_IS_BFD,
while LTO requires LD_IS_LLD.
I see another ld-option at 1043.
LDFLAGS_vmlinux += $(call ld-option,--pack-dyn-relocs=relr,-z
pack-relative-relocs)
Maybe, this is related to the issue
(although I did not attempt to reproduce it).
--
Best Regards
Masahiro Yamada
prev parent reply other threads:[~2024-05-12 13:15 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-05-11 11:18 Fwd: Incorrect thinlto cache directory path in Makefile Bagas Sanjaya
2024-05-12 13:04 ` Masahiro Yamada
2024-05-12 13:14 ` Masahiro Yamada [this message]
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