Re: [PATCH v3 5/5] loongarch: Use the -mno-relax cflags for gcc
On Thu, Jun 15, 2023 at 10:04:23AM +0800, Xiaotian Wu wrote: > 在 2023-06-13星期二的 20:09 +0800，Xi Ruoyao via Grub-devel写道： > > On Tue, 2023-06-13 at 13:39 +0200, Daniel Kiper wrote: > > > On Tue, Jun 13, 2023 at 05:06:35PM +0800, Xiaotian Wu wrote: > > > > Because the binutils of the loongarch architecture adds > > > > relaxation > > > > support [1], > > > > the next version of binutils will not be able to build grub. > > > > > > > > So we use the -mno-relax cflags to disable gcc to generate > > > > relaxation > > > > relocations to enhance the compatibility of grub. > > > > > > > > [1]: > > > > https://sourceware.org/git/?p=binutils-gdb.git;a=commit;h=56576f4a722b7398d35802ecf7d4185c27d6d69b > > > > > > > > Signed-off-by: Xiaotian Wu > > > > --- > > > > configure.ac | 12 > > > > 1 file changed, 12 insertions(+) > > > > > > > > diff --git a/configure.ac b/configure.ac > > > > index d9f088d12..cd3cc6ba8 100644 > > > > --- a/configure.ac > > > > +++ b/configure.ac > > > > @@ -874,6 +874,18 @@ if test "x$target_cpu" = xloongarch64; then > > > > TARGET_CFLAGS="$TARGET_CFLAGS -mno-explicit-relocs -fno-plt" > > > > TARGET_CCASFLAGS="$TARGET_CCASFLAGS -mno-explicit-relocs - > > > > fno- > > > > plt" > > > > fi > > > > + > > > > + AC_CACHE_CHECK([whether _mno_relax works], > > > > [grub_cv_cc_mno_relax], [ > > > > + CFLAGS="$TARGET_CFLAGS -mno-relax -Werror" > > > > + AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[]], [[]])], > > > > + [grub_cv_cc_mno_relax=yes], > > > > + [grub_cv_cc_mno_relax=no]) > > > > + ]) > > > > + if test "x$grub_cv_cc_mno_relax" = xyes; then > > > > + TARGET_CFLAGS="$TARGET_CFLAGS -mno-relax" > > > > + TARGET_CCASFLAGS="$TARGET_CCASFLAGS -mno-relax" > > > > + fi > > > > > > Could not you reuse sparc64 code which is ~100 lines below? If not > > > please make loongarch code as similar as possible to the sparc64 > > > one. > > > > More important reason is we need to try -Wa,-mno-relax along with - > > mno- > > relax, like SPARC64. GCC 13 and earlier does not accept -mno-relax, > > but > > the assembler itself can still generate R_LARCH_RELAX etc. So if a > > distro uses GCC 13 alongside Binutils 2.41, we'll need -Wa,-mno- > > relax. > > > > Note that Binutils 2.41 will be released in Feb 2024 but GCC 14 will > > be > > released in mid 2024 (Apr to Jun) so it can be expected that some > > distros will really use Binutils 2.41 and GCC 13. > > Code for sparc64 cannot be reused. > Because sparc64 sets LDFLAGS, and loongarch needs to set CFLAGS. > If only LDFLAGS is used on loongarch, gcc still generates .o files with > RELAX. The v4 LGTM but please add this explanation or something like that to the commit message and send v5. Daniel ___ Grub-devel mailing list Grub-devel@gnu.org https://lists.gnu.org/mailman/listinfo/grub-devel
Re: [PATCH v3 5/5] loongarch: Use the -mno-relax cflags for gcc
在 2023-06-13星期二的 20:09 +0800，Xi Ruoyao via Grub-devel写道： > On Tue, 2023-06-13 at 13:39 +0200, Daniel Kiper wrote: > > On Tue, Jun 13, 2023 at 05:06:35PM +0800, Xiaotian Wu wrote: > > > Because the binutils of the loongarch architecture adds > > > relaxation > > > support [1], > > > the next version of binutils will not be able to build grub. > > > > > > So we use the -mno-relax cflags to disable gcc to generate > > > relaxation > > > relocations to enhance the compatibility of grub. > > > > > > [1]: > > > https://sourceware.org/git/?p=binutils-gdb.git;a=commit;h=56576f4a722b7398d35802ecf7d4185c27d6d69b > > > > > > Signed-off-by: Xiaotian Wu > > > --- > > > configure.ac | 12 > > > 1 file changed, 12 insertions(+) > > > > > > diff --git a/configure.ac b/configure.ac > > > index d9f088d12..cd3cc6ba8 100644 > > > --- a/configure.ac > > > +++ b/configure.ac > > > @@ -874,6 +874,18 @@ if test "x$target_cpu" = xloongarch64; then > > > TARGET_CFLAGS="$TARGET_CFLAGS -mno-explicit-relocs -fno-plt" > > > TARGET_CCASFLAGS="$TARGET_CCASFLAGS -mno-explicit-relocs - > > > fno- > > > plt" > > > fi > > > + > > > + AC_CACHE_CHECK([whether _mno_relax works], > > > [grub_cv_cc_mno_relax], [ > > > + CFLAGS="$TARGET_CFLAGS -mno-relax -Werror" > > > + AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[]], [[]])], > > > + [grub_cv_cc_mno_relax=yes], > > > + [grub_cv_cc_mno_relax=no]) > > > + ]) > > > + if test "x$grub_cv_cc_mno_relax" = xyes; then > > > + TARGET_CFLAGS="$TARGET_CFLAGS -mno-relax" > > > + TARGET_CCASFLAGS="$TARGET_CCASFLAGS -mno-relax" > > > + fi > > > > Could not you reuse sparc64 code which is ~100 lines below? If not > > please make loongarch code as similar as possible to the sparc64 > > one. > > More important reason is we need to try -Wa,-mno-relax along with - > mno- > relax, like SPARC64. GCC 13 and earlier does not accept -mno-relax, > but > the assembler itself can still generate R_LARCH_RELAX etc. So if a > distro uses GCC 13 alongside Binutils 2.41, we'll need -Wa,-mno- > relax. > > Note that Binutils 2.41 will be released in Feb 2024 but GCC 14 will > be > released in mid 2024 (Apr to Jun) so it can be expected that some > distros will really use Binutils 2.41 and GCC 13. Code for sparc64 cannot be reused. Because sparc64 sets LDFLAGS, and loongarch needs to set CFLAGS. If only LDFLAGS is used on loongarch, gcc still generates .o files with RELAX. This point was also mentioned in mengqinggang's email: https://lists.gnu.org/archive/html/grub-devel/2023-06/msg00062.html > > -- > Xi Ruoyao > School of Aerospace Science and Technology, Xidian University > -- Best Regards Xiaotian Wu ___ Grub-devel mailing list Grub-devel@gnu.org https://lists.gnu.org/mailman/listinfo/grub-devel
Re: [PATCH v3 5/5] loongarch: Use the -mno-relax cflags for gcc
On Tue, 2023-06-13 at 13:39 +0200, Daniel Kiper wrote: > On Tue, Jun 13, 2023 at 05:06:35PM +0800, Xiaotian Wu wrote: > > Because the binutils of the loongarch architecture adds relaxation > > support [1], > > the next version of binutils will not be able to build grub. > > > > So we use the -mno-relax cflags to disable gcc to generate > > relaxation > > relocations to enhance the compatibility of grub. > > > > [1]: > > https://sourceware.org/git/?p=binutils-gdb.git;a=commit;h=56576f4a722b7398d35802ecf7d4185c27d6d69b > > > > Signed-off-by: Xiaotian Wu > > --- > > configure.ac | 12 > > 1 file changed, 12 insertions(+) > > > > diff --git a/configure.ac b/configure.ac > > index d9f088d12..cd3cc6ba8 100644 > > --- a/configure.ac > > +++ b/configure.ac > > @@ -874,6 +874,18 @@ if test "x$target_cpu" = xloongarch64; then > > TARGET_CFLAGS="$TARGET_CFLAGS -mno-explicit-relocs -fno-plt" > > TARGET_CCASFLAGS="$TARGET_CCASFLAGS -mno-explicit-relocs -fno- > > plt" > > fi > > + > > + AC_CACHE_CHECK([whether _mno_relax works], > > [grub_cv_cc_mno_relax], [ > > + CFLAGS="$TARGET_CFLAGS -mno-relax -Werror" > > + AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[]], [[]])], > > + [grub_cv_cc_mno_relax=yes], > > + [grub_cv_cc_mno_relax=no]) > > + ]) > > + if test "x$grub_cv_cc_mno_relax" = xyes; then > > + TARGET_CFLAGS="$TARGET_CFLAGS -mno-relax" > > + TARGET_CCASFLAGS="$TARGET_CCASFLAGS -mno-relax" > > + fi > > Could not you reuse sparc64 code which is ~100 lines below? If not > please make loongarch code as similar as possible to the sparc64 one. More important reason is we need to try -Wa,-mno-relax along with -mno- relax, like SPARC64. GCC 13 and earlier does not accept -mno-relax, but the assembler itself can still generate R_LARCH_RELAX etc. So if a distro uses GCC 13 alongside Binutils 2.41, we'll need -Wa,-mno-relax. Note that Binutils 2.41 will be released in Feb 2024 but GCC 14 will be released in mid 2024 (Apr to Jun) so it can be expected that some distros will really use Binutils 2.41 and GCC 13. -- Xi Ruoyao School of Aerospace Science and Technology, Xidian University -- Xi Ruoyao School of Aerospace Science and Technology, Xidian University ___ Grub-devel mailing list Grub-devel@gnu.org https://lists.gnu.org/mailman/listinfo/grub-devel
Re: [PATCH v3 5/5] loongarch: Use the -mno-relax cflags for gcc
On Tue, Jun 13, 2023 at 05:06:35PM +0800, Xiaotian Wu wrote: > Because the binutils of the loongarch architecture adds relaxation support > [1], > the next version of binutils will not be able to build grub. > > So we use the -mno-relax cflags to disable gcc to generate relaxation > relocations to enhance the compatibility of grub. > > [1]: > https://sourceware.org/git/?p=binutils-gdb.git;a=commit;h=56576f4a722b7398d35802ecf7d4185c27d6d69b > > Signed-off-by: Xiaotian Wu > --- > configure.ac | 12 > 1 file changed, 12 insertions(+) > > diff --git a/configure.ac b/configure.ac > index d9f088d12..cd3cc6ba8 100644 > --- a/configure.ac > +++ b/configure.ac > @@ -874,6 +874,18 @@ if test "x$target_cpu" = xloongarch64; then > TARGET_CFLAGS="$TARGET_CFLAGS -mno-explicit-relocs -fno-plt" > TARGET_CCASFLAGS="$TARGET_CCASFLAGS -mno-explicit-relocs -fno-plt" >fi > + > + AC_CACHE_CHECK([whether _mno_relax works], [grub_cv_cc_mno_relax], [ > +CFLAGS="$TARGET_CFLAGS -mno-relax -Werror" > +AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[]], [[]])], > + [grub_cv_cc_mno_relax=yes], > + [grub_cv_cc_mno_relax=no]) > + ]) > + if test "x$grub_cv_cc_mno_relax" = xyes; then > +TARGET_CFLAGS="$TARGET_CFLAGS -mno-relax" > +TARGET_CCASFLAGS="$TARGET_CCASFLAGS -mno-relax" > + fi Could not you reuse sparc64 code which is ~100 lines below? If not please make loongarch code as similar as possible to the sparc64 one. Daniel ___ Grub-devel mailing list Grub-devel@gnu.org https://lists.gnu.org/mailman/listinfo/grub-devel
Re: [PATCH v3 5/5] loongarch: Use the -mno-relax cflags for gcc
On 2023/6/13 17:06, Xiaotian Wu wrote: Because the binutils of the loongarch architecture adds relaxation support [1], the next version of binutils will not be able to build grub. We can simplify the sentence a bit, like "A working grub cannot be built with upcoming binutils and gcc, because linker relaxation was added [1] causing new unsupported relocations to appear in modules". So we use the -mno-relax cflags to disable gcc to generate relaxation relocations to enhance the compatibility of grub. Better mention the justification for not enabling relaxation, i.e. because bootloaders are not exactly performance-sensitive code. Also we can make the sentence more natural, like "So we pass -mno-relax to gcc if it is supported, to disable relaxation and make grub forward-compatible with new toolchains". [1]: https://sourceware.org/git/?p=binutils-gdb.git;a=commit;h=56576f4a722b7398d35802ecf7d4185c27d6d69b Signed-off-by: Xiaotian Wu --- configure.ac | 12 1 file changed, 12 insertions(+) diff --git a/configure.ac b/configure.ac index d9f088d12..cd3cc6ba8 100644 --- a/configure.ac +++ b/configure.ac @@ -874,6 +874,18 @@ if test "x$target_cpu" = xloongarch64; then TARGET_CFLAGS="$TARGET_CFLAGS -mno-explicit-relocs -fno-plt" TARGET_CCASFLAGS="$TARGET_CCASFLAGS -mno-explicit-relocs -fno-plt" fi + + AC_CACHE_CHECK([whether _mno_relax works], [grub_cv_cc_mno_relax], [ I don't have a strong opinion as to whether a justification should be put here above the check though. +CFLAGS="$TARGET_CFLAGS -mno-relax -Werror" +AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[]], [[]])], + [grub_cv_cc_mno_relax=yes], + [grub_cv_cc_mno_relax=no]) + ]) + if test "x$grub_cv_cc_mno_relax" = xyes; then +TARGET_CFLAGS="$TARGET_CFLAGS -mno-relax" +TARGET_CCASFLAGS="$TARGET_CCASFLAGS -mno-relax" + fi + TARGET_CFLAGS="$TARGET_CFLAGS -Wa,-mla-global-with-abs" TARGET_CCASFLAGS="$TARGET_CCASFLAGS -Wa,-mla-global-with-abs" fi ___ Grub-devel mailing list Grub-devel@gnu.org https://lists.gnu.org/mailman/listinfo/grub-devel
[PATCH v3 5/5] loongarch: Use the -mno-relax cflags for gcc
Because the binutils of the loongarch architecture adds relaxation support [1], the next version of binutils will not be able to build grub. So we use the -mno-relax cflags to disable gcc to generate relaxation relocations to enhance the compatibility of grub. [1]: https://sourceware.org/git/?p=binutils-gdb.git;a=commit;h=56576f4a722b7398d35802ecf7d4185c27d6d69b Signed-off-by: Xiaotian Wu --- configure.ac | 12 1 file changed, 12 insertions(+) diff --git a/configure.ac b/configure.ac index d9f088d12..cd3cc6ba8 100644 --- a/configure.ac +++ b/configure.ac @@ -874,6 +874,18 @@ if test "x$target_cpu" = xloongarch64; then TARGET_CFLAGS="$TARGET_CFLAGS -mno-explicit-relocs -fno-plt" TARGET_CCASFLAGS="$TARGET_CCASFLAGS -mno-explicit-relocs -fno-plt" fi + + AC_CACHE_CHECK([whether _mno_relax works], [grub_cv_cc_mno_relax], [ +CFLAGS="$TARGET_CFLAGS -mno-relax -Werror" +AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[]], [[]])], + [grub_cv_cc_mno_relax=yes], + [grub_cv_cc_mno_relax=no]) + ]) + if test "x$grub_cv_cc_mno_relax" = xyes; then +TARGET_CFLAGS="$TARGET_CFLAGS -mno-relax" +TARGET_CCASFLAGS="$TARGET_CCASFLAGS -mno-relax" + fi + TARGET_CFLAGS="$TARGET_CFLAGS -Wa,-mla-global-with-abs" TARGET_CCASFLAGS="$TARGET_CCASFLAGS -Wa,-mla-global-with-abs" fi -- 2.40.1 ___ Grub-devel mailing list Grub-devel@gnu.org https://lists.gnu.org/mailman/listinfo/grub-devel
