On Tue, Oct 4, 2022 at 2:10 AM Nathan Chancellor <nathan@xxxxxxxxxx> wrote:
>
> On Mon, Oct 03, 2022 at 03:11:06AM +0900, Masahiro Yamada wrote:
> > CONFIG_DEBUG_INFO_DWARF_TOOLCHAIN_DEFAULT passes the -g option to the
> > command line. The actual DWARF version is up to the toolchain.
> >
> > The combination of GCC and GAS works fine, and Clang with the integrated
> > assembler is good too.
> >
> > The combination of Clang and GAS is a bit tricky, but at least, the
> > default -g flag worked until LLVM 14 was released because Clang <=13
> > defaults to DWARF v4.
> >
> > Clang 14 switched to DWARF v5 by default.
> >
> > Now, CONFIG_DEBUG_INFO_DWARF_TOOLCHAIN_DEFAULT has the same issue as
> > addressed by commit 98cd6f521f10 ("Kconfig: allow explicit opt in to
> > DWARF v5").
> >
> > CONFIG_DEBUG_INFO_DWARF_TOOLCHAIN_DEFAULT=y for Clang >= 14 and
> > GAS < 2.35 produces a ton of errors like follows:
> >
> > /tmp/main-c2741c.s: Assembler messages:
> > /tmp/main-c2741c.s:109: Error: junk at end of line, first unrecognized character is `"'
> > /tmp/main-c2741c.s:109: Error: file number less than one
> >
> > Add 'depends on' to check toolchains.
> >
> > Signed-off-by: Masahiro Yamada <masahiroy@xxxxxxxxxx>
> > ---
> >
> > lib/Kconfig.debug | 1 +
> > 1 file changed, 1 insertion(+)
> >
> > diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
> > index f4b2165f24db..cc90414d492e 100644
> > --- a/lib/Kconfig.debug
> > +++ b/lib/Kconfig.debug
> > @@ -253,6 +253,7 @@ config DEBUG_INFO_NONE
> > config DEBUG_INFO_DWARF_TOOLCHAIN_DEFAULT
> > bool "Rely on the toolchain's implicit default DWARF version"
> > select DEBUG_INFO
> > + depends on !CC_IS_CLANG || AS_IS_LLVM || CLANG_VERSION < 140000 || (AS_IS_GNU && AS_VERSION >= 23502)
> > help
> > The implicit default version of DWARF debug info produced by a
> > toolchain changes over time.
> > --
> > 2.34.1
> >
> >
>
> Could we do something like this instead? Bikeshed the configuration
> names as much as you want but we are duplicating most of this
> conditional in a few different places so it would be good to consolidate
> those in my opinion. Even though the DWARF4 and DWARF5 conditions are
> the same, they might diverge so I think it makes sense to keep them
> separate.
>
> diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
> index cc90414d492e..8e34a639cd40 100644
> --- a/lib/Kconfig.debug
> +++ b/lib/Kconfig.debug
> @@ -231,6 +231,17 @@ config DEBUG_INFO
> in the "Debug information" choice below, indicating that debug
> information will be generated for build targets.
>
> +config CC_AND_AS_SUPPORT_DWARF4
> + def_bool !CC_IS_CLANG || AS_IS_LLVM || (AS_IS_GNU && AS_VERSION >= 23502)
> +
> +config CC_AND_AS_SUPPORT_DWARF5
> + def_bool !CC_IS_CLANG || AS_IS_LLVM || (AS_IS_GNU && AS_VERSION >= 23502)
> +
> +config CC_AND_AS_SUPPORT_DWARF_DEFAULT
> + bool
> + default y if CC_AND_AS_SUPPORT_DWARF5 && (CLANG_VERSION >= 140000 || GCC_VERSION >= 110000)
> + default y if CC_AND_AS_SUPPORT_DWARF4 && (CLANG_VERSION < 140000 || GCC_VERSION < 110000)
No, this is an overkill.
In my patch, you can enable DEBUG_INFO_DWARF_TOOLCHAIN_DEFAULT
for the combination of:
CC_IS_CLANG=y
CLANG_VERSION < 140000
AS_IS_GNU=y
AS_VERSION < 23502
But, your code disallows it.
You are requiring binutils 2.35.2 for Clang+GAS, but
it is not necessary.
> choice
> prompt "Debug information"
> depends on DEBUG_KERNEL
> @@ -253,7 +264,7 @@ config DEBUG_INFO_NONE
> config DEBUG_INFO_DWARF_TOOLCHAIN_DEFAULT
> bool "Rely on the toolchain's implicit default DWARF version"
> select DEBUG_INFO
> - depends on !CC_IS_CLANG || AS_IS_LLVM || CLANG_VERSION < 140000 || (AS_IS_GNU && AS_VERSION >= 23502)
> + depends on CC_AND_AS_SUPPORT_DWARF_DEFAULT
> help
> The implicit default version of DWARF debug info produced by a
> toolchain changes over time.
> @@ -265,7 +276,7 @@ config DEBUG_INFO_DWARF_TOOLCHAIN_DEFAULT
> config DEBUG_INFO_DWARF4
> bool "Generate DWARF Version 4 debuginfo"
> select DEBUG_INFO
> - depends on !CC_IS_CLANG || AS_IS_LLVM || (AS_IS_GNU && AS_VERSION >= 23502)
> + depends on CC_AND_AS_SUPPORT_DWARF4
> help
> Generate DWARF v4 debug info. This requires gcc 4.5+, binutils 2.35.2
> if using clang without clang's integrated assembler, and gdb 7.0+.
> @@ -277,7 +288,7 @@ config DEBUG_INFO_DWARF4
> config DEBUG_INFO_DWARF5
> bool "Generate DWARF Version 5 debuginfo"
> select DEBUG_INFO
> - depends on !CC_IS_CLANG || AS_IS_LLVM || (AS_IS_GNU && AS_VERSION >= 23502)
> + depends on CC_AND_AS_SUPPORT_DWARF5
> help
> Generate DWARF v5 debug info. Requires binutils 2.35.2, gcc 5.0+ (gcc
> 5.0+ accepts the -gdwarf-5 flag but only had partial support for some
--
Best Regards
Masahiro Yamada
