| Message ID | 20221002181107.51286-3-masahiroy@kernel.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | Kconfig.debug: make more efforts to fix CONFIG_DEBUG_INFO for Clang+GAS | expand |
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@kernel.org> > --- > > 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 <nathan@kernel.org> 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@kernel.org> > > --- > > > > 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
On Tue, Oct 04, 2022 at 05:18:49AM +0900, Masahiro Yamada wrote: > On Tue, Oct 4, 2022 at 2:10 AM Nathan Chancellor <nathan@kernel.org> 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@kernel.org> > > > --- > > > > > > 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 <nathan@kernel.org> 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
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.
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@kernel.org> --- lib/Kconfig.debug | 1 + 1 file changed, 1 insertion(+)