Re: [PATCH v2 0/5] loongarch: add relaxation support

[mengqinggang]

LDFLAGS do not affect relocations generation. If just modify LDFLAGS,
grub still needs to process relaxation relocations.

在 2023/6/13 下午2:22, Xiaotian Wu 写道:

> 在 2023-06-13星期二的 11:25 +0800，mengqinggang写道：
> > Is this  patch used to check if ld supports --no-relax option?
> > It need to pass -mno-relax option to as or gcc to disable binutils
> > generate relaxation relocations.
> >
> >       
> Check "-mno-relax" and "-Wl,--no-relax" in order, if "-mno-relax" is
> valid, then LDFLAGS="$LDFLAGS -mno-relax"; if "-Wl,--no-relax" is
> valid, then LDFLAGS="$LDFLAGS -Wl,--no-relax", otherwise report an
> error.
>
> The full code is here:
> https://github.com/loongarch64/grub/blob/dev-master/configure.ac#L976-L1000
>
> Using binutils 2.40, the LDFLAGS value displayed in the Makefile is as
> follows, without "-mno-relax" in it:
>
> TARGET_LDFLAGS =  "-Wl,--no-relax -no-pie -Wl,--build-id=none"
>
> > 在 2023/6/13 上午10:37, Xiaotian Wu 写道:
> >  
> > > New patch is ready:
> > > https://github.com/loongarch64/grub/commits/dev-master
> > >
> > > I need your help to confirm that binutils-2.40 and binutils-dev
> > > code
> > > have the same behavior when using compile options, thanks.
> > >
> > > 在 2023-06-12星期一的 06:35 +0800，Xi Ruoyao via Grub-devel写道：
> > >  
> > > > On Wed, 2023-06-07 at 15:34 +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 added the R_LARCH_B16, R_LARCH_B21 and R_LARCH_RELAX
> > > > > relocations
> > > > > to enhance grub compatibility.
> > > > >             
> > > > Wouldn't it be easier to just pass -mno-relax to the toolchain
> > > > when
> > > > we
> > > > build GRUB?  I don't think it makes too much sense to perform
> > > > relaxation
> > > > on a boot loader.  The boot loader is generally the coldest code
> > > > paths
> > > > in a system, so relaxing it won't give any real benefit (well, if
> > > > you
> > > > reboot a system 100 times you may finally save one second), but
> > > > increases the maintenance burden.
> > > >
> > > > Consider a new relaxation pattern is added after we release GRUB
> > > > 2.12. 
> > > > Then if we simply pass -mno-relax, GRUB 2.12 will continue to
> > > > work. 
> > > > But
> > > > if we try to "support" relaxation this way, every distro will
> > > > have to
> > > > patch GRUB 2.12 when the toolchain is updated.
> > > >
> > > >  
> > > > > [1]:
> > > > > https://sourceware.org/git/?p=binutils-gdb.git;a=commit;h=56576f4a722b7398d35802ecf7d4185c27d6d69b
> > > > >
> > > > > v1->v2:
> > > > > - split patch
> > > > > - drop cast code
> > > > >
> > > > > Xiaotian Wu (5):
> > > > >   Use the correct format specifier for formatted output
> > > > >   loongarch: Optimize code using pc variable
> > > > >   loongarch: Rename function names
> > > > >   loongarch: Add ELF relocation types documentation and
> > > > > comments
> > > > >   loongarch: Add relaxation support
> > > > >
> > > > >  grub-core/kern/arm64/dl_helper.c       |  4 +-
> > > > >  grub-core/kern/loongarch64/dl.c        | 21 +++++++-
> > > > >  grub-core/kern/loongarch64/dl_helper.c | 72
> > > > > ++++++++++++++++++++++++-
> > > > > -
> > > > >  include/grub/elf.h                     |  3 ++
> > > > >  include/grub/loongarch64/reloc.h       |  6 ++-
> > > > >  util/grub-mkimagexx.c                  | 28 ++++++++--
> > > > >  util/grub-module-verifier.c            |  3 ++
> > > > >  7 files changed, 124 insertions(+), 13 deletions(-)
> > > > >
> > > > >             
> > > >           
> > >         
> >  
> >       
>