Re: [PATCH v9 01/16] tracing: move function tracer options to Kconfig (causing parisc build failures)

[Guenter Roeck]

On Fri, Dec 11, 2020 at 10:46:18AM -0800, Sami Tolvanen wrote:
> Move function tracer options to Kconfig to make it easier to add
> new methods for generating __mcount_loc, and to make the options
> available also when building kernel modules.
> 
> Note that FTRACE_MCOUNT_USE_* options are updated on rebuild and
> therefore, work even if the .config was generated in a different
> environment.
> 
> Signed-off-by: Sami Tolvanen <samitolvanen@xxxxxxxxxx>
> Acked-by: Steven Rostedt (VMware) <rostedt@xxxxxxxxxxx>

With this patch in place, parisc:allmodconfig no longer builds.

Error log:
Arch parisc is not supported with CONFIG_FTRACE_MCOUNT_RECORD at scripts/recordmcount.pl line 405.
make[2]: *** [scripts/mod/empty.o] Error 2

Due to this problem, CONFIG_FTRACE_MCOUNT_RECORD can no longer be
enabled in parisc builds. Since that is auto-selected by DYNAMIC_FTRACE,
DYNAMIC_FTRACE can no longer be enabled, and with it everything that
depends on it.

Bisect log attached.

Guenter

---
# bad: [414eece95b98b209cef0f49cfcac108fd00b8ced] Merge tag 'clang-lto-v5.12-rc1-part2' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux
# good: [b12b47249688915e987a9a2a393b522f86f6b7ab] Merge tag 'powerpc-5.12-1' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux
git bisect start '414eece95b98' 'b12b47249688'
# bad: [f6e1e1d1e149802ed4062fa514c2d184d30aacdf] Merge tag 'gfs2-for-5.12' of git://git.kernel.org/pub/scm/linux/kernel/git/gfs2/linux-gfs2
git bisect bad f6e1e1d1e149802ed4062fa514c2d184d30aacdf
# bad: [79db4d2293eba2ce6265a341bedf6caecad5eeb3] Merge tag 'clang-lto-v5.12-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux
git bisect bad 79db4d2293eba2ce6265a341bedf6caecad5eeb3
# good: [9d5032f97e9e0655e8c507ab1f43237e31520b00] dt-bindings: mediatek: mt8192: Fix dt_binding_check warning
git bisect good 9d5032f97e9e0655e8c507ab1f43237e31520b00
# good: [f81f213850ca84b3d5e59e17d17acb2ecfc24076] Merge tag 'for-linus-5.12-1' of git://github.com/cminyard/linux-ipmi
git bisect good f81f213850ca84b3d5e59e17d17acb2ecfc24076
# bad: [112b6a8e038d793d016e330f53acb9383ac504b3] arm64: allow LTO to be selected
git bisect bad 112b6a8e038d793d016e330f53acb9383ac504b3
# bad: [3578ad11f3fba07e64c26d8db68cfd3dde28c59e] init: lto: fix PREL32 relocations
git bisect bad 3578ad11f3fba07e64c26d8db68cfd3dde28c59e
# bad: [22d429e75f24d114d99223389d6ba7047e952e32] kbuild: lto: limit inlining
git bisect bad 22d429e75f24d114d99223389d6ba7047e952e32
# bad: [dc5723b02e523b2c4a68667f7e28c65018f7202f] kbuild: add support for Clang LTO
git bisect bad dc5723b02e523b2c4a68667f7e28c65018f7202f
# bad: [3b15cdc15956673ba1551d79bceae471436ac6a9] tracing: move function tracer options to Kconfig
git bisect bad 3b15cdc15956673ba1551d79bceae471436ac6a9
# first bad commit: [3b15cdc15956673ba1551d79bceae471436ac6a9] tracing: move function tracer options to Kconfig