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Olliver Schinagl

2022-Jul-26 20:30 UTC

[klibc] Mips cross-compiling whos

Hey list,

I'm trying to cross-compile klibc on mips. As I packaged it for alpine 
before, I figured it shouldn't be that hard ;) Sadly, alpine doesn't 
support mips[32|64] so I have to cross-compile it.


I'm doing this from within an alpine based docker container, using a 
simple script (setup vars, unzip, make).


There's a few things I don't understand why they are the way they are, 
but have a somewhat easy work-around (haven't spend time to figure out 
if it is the correct one at all or not :p).


First, this work-around I have also in the alpine packages, since it's 
just shuffling stuff around, but keeping all definitions, I don't 
mind/care much.

```

 ?? ???? if [ ! -e 'usr/include/sys/sysinfo.h.orig' ]; then
 ?? ???? ??? mv 'usr/include/sys/sysinfo.h' \
 ?? ???? ??? ?? 'usr/include/sys/sysinfo.h.orig'
 ?? ???? fi
 ?? ???? cat \
 ?? ???? ??? '/usr/include/linux/sysinfo.h' \
 ?? ???? ??? 'usr/include/sys/sysinfo.h.orig' > \
 ?? ???? ??? 'usr/include/sys/sysinfo.h'
```

excuse the uglyness :p


Secondly, specificaly on mips, I get re-definition errors, I haven't 
looked into detail why `f_owner_ex` is redefined, but I use the 
following here:

```

 ?? ???? sed -i \
 ?? ???? ??? -e '/^typedef struct flock {$/i # define 
HAVE_ARCH_STRUCT_FLOCK/' \
 ?? ???? ??? -e '/^struct f_owner_ex {$/,+6d' \
 ?? ???? ??? 'usr/include/arch/mips/klibc/archfcntl.h'

```


Lastly, _KLIBC_USE_RT_SIG supposedly 'can' be used on mips, but it 
causes a `-1` unnamed array definition error, so 'can' means 'does
not
needed to be', so I just disabled it.


```

 ?? ???? sed -i 's|^\(#define _KLIBC_USE_RT_SIG \).*$|\1 0|' 
'usr/include/arch/mips/klibc/archconfig.h'

```


Now, to compile, I use

```

 ?? ???? make \
 ?? ???? ???? KBUILD_REPRODUCIBLE=1 \
 ?? ???? ???? KLIBCARCH="mips" \
 ?? ???? ???? KLIBCKERNELSRC='/usr/' \
 ?? ???? ???? ;

```

with the kernel header package installed under '/usr'; but I'm
thrown a
`syscalls.h` missing header error, that I can't figure out. It seems 
like `syscalls.pl` would generate them, but I get no warnings or errors 
on the failure thereof, which kinda puts me at a loss.

```

usr/klibc/sigsuspend.c:8:10: fatal error: klibc/havesyscall.h: No such 
file or directory
 ??? 8 | #include <klibc/havesyscall.h>
 ????? |????????? ^~~~~~~~~~~~~~~~~~~~~

```

Any idea what's missing, what's failing? Perl is available and working;

This is perl 5, version 34, subversion 1 (v5.34.1) built for 
x86_64-linux-thread-multi
and gcc is working fine for the other stuffs

mips-mti-elf-gcc (Alpine Linux) 11.2.0


Any thoughts or points would be greatly appreciated ...


Olliver


P.S. I'm not subscribed to the list; so please keep me in the CC :)

Ben Hutchings

2022-Aug-01 18:21 UTC

head link

[klibc] Mips cross-compiling whos

On Tue, 2022-07-26 at 22:30 +0200, Olliver Schinagl
wrote:> Hey list,
> 
> I'm trying to cross-compile klibc on mips. As I packaged it for alpine 
> before, I figured it shouldn't be that hard ;) Sadly, alpine
doesn't
> support mips[32|64] so I have to cross-compile it.
Cross-compilation should work, and I regularly test this for all the
architectures that Debian provides cross-compilers for.
> I'm doing this from within an alpine based docker container, using a 
> simple script (setup vars, unzip, make).
> 
> 
> There's a few things I don't understand why they are the way they
are,
> but have a somewhat easy work-around (haven't spend time to figure out 
> if it is the correct one at all or not :p).
> 
> 
> First, this work-around I have also in the alpine packages, since it's 
> just shuffling stuff around, but keeping all definitions, I don't 
> mind/care much.
> 
> ```
> 
>  ?? ???? if [ ! -e 'usr/include/sys/sysinfo.h.orig' ]; then
>  ?? ???? ??? mv 'usr/include/sys/sysinfo.h' \
>  ?? ???? ??? ?? 'usr/include/sys/sysinfo.h.orig'
>  ?? ???? fi
>  ?? ???? cat \
>  ?? ???? ??? '/usr/include/linux/sysinfo.h' \
>  ?? ???? ??? 'usr/include/sys/sysinfo.h.orig' > \
>  ?? ???? ??? 'usr/include/sys/sysinfo.h'
> ```
This doesn't make any sense to me.  Our sys/sysinfo.h already includes
<linux/kernel.h>, which includes <linux/sysinfo.h>.
> 
> excuse the uglyness :p
> 
> 
> Secondly, specificaly on mips, I get re-definition errors, I haven't 
> looked into detail why `f_owner_ex` is redefined, but I use the 
> following here:
> 
> ```
> 
>  ?? ???? sed -i \
>  ?? ???? ??? -e '/^typedef struct flock {$/i # define 
> HAVE_ARCH_STRUCT_FLOCK/' \
>  ?? ???? ??? -e '/^struct f_owner_ex {$/,+6d' \
>  ?? ???? ??? 'usr/include/arch/mips/klibc/archfcntl.h'
> 
> ```
It's also defined in <asm/fcntl.h>, which I think is "wrong"
on MIPS.
We try to prevent including both <klibc/archfcntl.h> and
<asm/fcntl.h>,
though it looks like that check broke about 10 years ago in the UAPI
split!
> Lastly, _KLIBC_USE_RT_SIG supposedly 'can' be used on mips, but it 
> causes a `-1` unnamed array definition error, so 'can' means
'does not
> needed to be', so I just disabled it.
> 
> 
> ```
> 
>  ?? ???? sed -i 's|^\(#define _KLIBC_USE_RT_SIG \).*$|\1 0|' 
> 'usr/include/arch/mips/klibc/archconfig.h'
> 
> ```
This is not a configuration option.  You can't change it without
changing the architecture implementation too.

[...]> Now, to compile, I use
> 
> ```
> 
>  ?? ???? make \
>  ?? ???? ???? KBUILD_REPRODUCIBLE=1 \
>  ?? ???? ???? KLIBCARCH="mips" \
>  ?? ???? ???? KLIBCKERNELSRC='/usr/' \
>  ?? ???? ???? ;
> 
> ```[...]

This causes klibc to use the kernel headers for the build machine's
architecture, which is wrong for cross-builds.  This is probably the
source of all or most of the errors.

If you have a working cross-compiler then it must have a copy of the
kernel headers for the target architecture installed somewhere, and you
need to tell klibc where that is or link to it.  I don't know how
Alpine packages cross-tools, but this is what we do in Debian:
https://salsa.debian.org/kernel-team/klibc/-/blob/master/debian/rules#L58

Ben.

-- 
Ben Hutchings
Larkinson's Law: All laws are basically false.
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klibc - Aug 2022 - Mips cross-compiling whos

[klibc] Mips cross-compiling whos

[klibc] Mips cross-compiling whos