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 <[email protected]>
---
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
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 <[email protected]>
> ---
>
> 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)
+
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
On Tue, Oct 4, 2022 at 2:10 AM Nathan Chancellor <[email protected]> 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 <[email protected]>
> > ---
> >
> > 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
On Tue, Oct 04, 2022 at 05:18:49AM +0900, Masahiro Yamada wrote:
> On Tue, Oct 4, 2022 at 2:10 AM Nathan Chancellor <[email protected]> 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 <[email protected]>
> > > ---
> > >
> > > 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.
Ah, I figured that part was necessary because of the condition added to
CONFIG_DEBUG_INFO_DWARF4 by commit 32ef9e5054ec ("Makefile.debug:
re-enable debug info for .S files") but I see now that was because of
some binutils behavior that you pointed out on Nick's v2 of that change,
which I failed to pay attention to because I had already reviewed the
change and did not read subsequent reviews/revisions as I should have,
so my apologies.
https://lore.kernel.org/CAK7LNATWDH01=ZKLnsxc0vcib1zGDbEq8jLQwhWP7HkkmSb_Mw@mail.gmail.com/
Regardless, I still think the duplication in these conditions is
unfortunate and I would like to see it cleaned up in some way but I
don't have a strong opinion on the matter. To the original change:
Reviewed-by: Nathan Chancellor <[email protected]>
Once these are applied to linux-kbuild, I will send a v2 of my RISC-V
fix.
> > 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