m68k fdpic toolchain?

m68k fdpic toolchain?

[Rob Landley]

Now that we can build fdpic support in the kernel, does a _compiler_ exist?

https://lore.kernel.org/linux-mm/20220428033319.239341-1-gerg@linux-m68k.org/T/

I built buildroot's mcf5208evb defconfig and booted it under qemu, but it's
binflt, which I'm not adding to my test system's package dependencies.

I've already got an sh2 fdpic test system, but it's on real hardware, not qemu.
(The toolchain patches for that are at
https://github.com/richfelker/musl-cross-make/blob/master/patches/binutils-2.33.1/0001-j2.diff
and
https://github.com/richfelker/musl-cross-make/blob/master/patches/gcc-11.2.0/0003-j2.diff
by the way. I'm happy to use similar out-of-tree patches for m68k in the short
term, if that's what's available...)

Rob

Re: m68k fdpic toolchain?

[Greg Ungerer]

On 28/1/24 20:27, Rob Landley wrote:
> Now that we can build coldfire fdpic support in the kernel, does a _compiler_ exist?

No, no fdopic support has been added to bgcc for m68k/coldfire.


> https://lore.kernel.org/linux-mm/20220428033319.239341-1-gerg@linux-m68k.org/T/
> 
> I built buildroot's mcf5208evb defconfig and booted it under qemu, but it's
> binflt, which I'm not adding to my test system's package dependencies. According
> to fs/Kconfig.binfmt:
> 
>   config BINFMT_ELF_FDPIC
>          bool "Kernel support for FDPIC ELF binaries"
>          default y if !BINFMT_ELF
>          depends on ARM || ((M68K || RISCV || SUPERH || XTENSA) && !MMU)
> 
> So I can select it, but in gcc's current git "grep -irl fdpic gcc/config" only
> has hits in the sh, arm, frv, and bfin directories.

As-is today you can load and run PIE ELF binaries using this support.
No additional changes to binutils or gcc required for that.

Regards
Greg



> Two of those three (frv and blackfin) were jettisoned by linux-kernel due to
> loss of expertise in the development community. I've already got an sh2 fdpic
> test system, but only on real hardware, not qemu (which decided to add
> qemu-system-sh4 instead of qemu-system-sh way back when, and thus never
> populated the rest of the family).
> 
> I'm happy to use out-of-tree patches for m68k if that's what's available, but I
> haven't been able to find any. I assume that enabling fdpic means the ABI was
> documented specifying the registers for the extra segments...?
> 
> Rob
> 

m68k fdpic toolchain?

[Rob Landley]

Now that we can build coldfire fdpic support in the kernel, does a _compiler_ exist?

https://lore.kernel.org/linux-mm/20220428033319.239341-1-gerg@linux-m68k.org/T/

I built buildroot's mcf5208evb defconfig and booted it under qemu, but it's
binflt, which I'm not adding to my test system's package dependencies. According
to fs/Kconfig.binfmt:

 config BINFMT_ELF_FDPIC
        bool "Kernel support for FDPIC ELF binaries"
        default y if !BINFMT_ELF
        depends on ARM || ((M68K || RISCV || SUPERH || XTENSA) && !MMU)

So I can select it, but in gcc's current git "grep -irl fdpic gcc/config" only
has hits in the sh, arm, frv, and bfin directories.

Two of those three (frv and blackfin) were jettisoned by linux-kernel due to
loss of expertise in the development community. I've already got an sh2 fdpic
test system, but only on real hardware, not qemu (which decided to add
qemu-system-sh4 instead of qemu-system-sh way back when, and thus never
populated the rest of the family).

I'm happy to use out-of-tree patches for m68k if that's what's available, but I
haven't been able to find any. I assume that enabling fdpic means the ABI was
documented specifying the registers for the extra segments...?

Rob