[Tinycc-devel] regression testing with a complete i486-tcc-linux-musl.iso distribution

[Michael Ackermann]

Thanks grischka!

With re-ordered sections linux-2.4.37.11 compiles/links and boots again.
Too i re-tested recent commit f0cd0fbe1b0b0465c87f9507299b468a0b208cf7
against a complete(!) system set of builds that i zipped into ~500 ebuilds here,
fully supported by tcc for x86 already. Fully supporting tcc with
crossdev/portage was a hell of a hackjob.

And I was bug-hunting and bisecting various tcc versions, kernel versions and
patchsets for month to salvage Linux-2.4 compilation with tcc (the section
layout issue wasn't the only one), without any known-good working baseline
up until recently.

FYI:
That is, for regression testing tcc which would have prevented me wasting weeks
of bisecting, it is now possible:
- to regularly compile/link/boot linux-2.4 x86
- and a complete set of ~500 packages that i can support with tcc already
  (removed all direct and transitive c++ dependencies, among other patches)

With plans to emit a complete i486-tcc-linux-musl.iso distribution to work with,
I've already spotted other minor regressions. I'll try to fix and/or report
those as best as i can, and will announce on the mailing list once the tcc-linux
distribution is available.

Furthermore i cannot support dynamic-linking with tcc yet, because
musl-libc libc.so dynamic loader crashes when compiled/linked with tcc
(bootstrappable.org got some patches for musl-libc for support with tcc
statically linked);
Hence i have to re-bundle what's currently maintained for tcc without
ebuilds/portage/crossdev (python needs dynamic linking and fails with tcc),
statically linked.
Once the distribution is ready and available as a stable(!) baseline i'll
summarize ISSUES, so these can be re-produced and verified against it easily
without duplicate efforts.

Grischka, if that's ok and doesn't cause too much confusion,
i would appreciate if efforts are coordinated to avoid future regressions that
required bi-secting accross more than 100 commits;
for example release tag for 0.9.27 dates back 7 years already, and 0.9.28 seems
not sufficiently stabilized yet.
Anyway, too i am planning to converge and re-integrate the tcc-toolchain
system profile that i got with bootstrappable.org
That is, currently i cannot publish yet, since it is too much cleanup work
remaining to finalize a complete i486-tcc-linux-musl.iso distribution to work
and test with, and i rather keep tcc synced to latest HEAD for this ;)

Regards.
aggi

On 2024-11-13 14:00, grischka via Tinycc-devel wrote:
> On 13.11.2024 00:41, Vad Rulezz wrote:
> > I'll look into it, having ability to build/boot linux is a nice thing.
> >
> > I think the issue is may be the sections ordering while linking. Well, 
> > maybe something else too, but it't unlikely there is a lot of brokiness..
> 
> To have executable code come first in the "vmlinux" non-elf binary
> you can try this:
> 
> in tccelf.c:sort_sections():
>               if (s->sh_flags & SHF_EXECINSTR)
> -                k = 0x70;
> +                k = 0x30;
> 
> Currently (with k=0x70) it would put ro-data first.
> 
> -- grischka
> 
> >
> >
> > Vad Rulezz
> >
> > On 11/13/24 2:24 AM, Michael Ackermann via Tinycc-devel wrote:
> >> This one from seyko2 is a good start for AoT compiling/linking linux-2.4:
> >> https://github.com/seyko2/tccboot
> >> FYI, for 16bit real-mode bootcode assembly binutils-as is needed,
> >> 32bit compiling/assembly/linking is handled nicely by tcc.
> >> and i've mentioned the latest commit-id on mob branch that i tested with.
> >>
> >> Myself too had tested tccboot JiT, which i succeeded with once with some 
> >> updated
> >> tcc mob branch version linked against, but didn't test any further, not 
> >> yet.
> >> tccboot is available from bellard.org
> >>
> >> anyway, the regression on tcc mob branch seems rather severe, although it's
> >> disclosed by kernel compilation for x86 only, i suspect it potentially 
> >> affects
> >> various other test-cases and architectures.
> >>
> >> On 2024-11-13 00:56, Vad Rulezz wrote:
> >>> Hello Michael,
> >>>
> >>> On 11/12/24 10:27 PM, Michael Ackermann via Tinycc-devel wrote:
> >>>> The revert/backout diff that i could confirm that tcc succeeds 
> >>>> compiling/linking
> >>>> kernel with is attached.
> >>>
> >>> Can you share a script or somewhat detailed instructions on how to build
> >>> linux kernel with TCC?
> >>>
> >>>
> >>> Vad Rulezz
> >>>
> >>> _______________________________________________
> >>> Tinycc-devel mailing list
> >>> Tinycc-devel@nongnu.org
> >>> https://lists.nongnu.org/mailman/listinfo/tinycc-devel
> >>
> >>
> >> _______________________________________________
> >> Tinycc-devel mailing list
> >> Tinycc-devel@nongnu.org
> >> https://lists.nongnu.org/mailman/listinfo/tinycc-devel
> >>
> >
> > _______________________________________________
> > Tinycc-devel mailing list
> > Tinycc-devel@nongnu.org
> > https://lists.nongnu.org/mailman/listinfo/tinycc-devel
> 
> 
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