I did a topic a little earlier about compiling a compiler for processor Geode LX800.
The bottom line is that I have a processor on which I want to compile the program, is an i586 architecture.

The official documentation says that "... the core is a combination of Intel Pentium ® processor, AMD Athlon™ processor, and AMD Geode LX processor specific instructions." - this means that the processor architecture is < i686. And judging by the fact that Linux gives a description when calling uname:

# uname -m
i586

This suggests that the processor is CLEARLY i586.
The problem is that I can't assemble the software I need for this processor, since it is automatically assembled for i686.
What have I done?
I built an ldc compiler on this machine:

# ldc2 --version
LDC - the LLVM D compiler (1.30.0-git-32f5a35):
  based on DMD v2.100.1 and LLVM 10.0.1
  built with DMD32 D Compiler v2.086.1
  Default target: i686-pc-linux-gnu
  Host CPU: geode
  http://dlang.org - http://wiki.dlang.org/LDC

  Registered Targets:
    x86    - 32-bit X86: Pentium-Pro and above
    x86-64 - 64-bit X86: EM64T and AMD64

And when I try to compile the program through it, I create a binary file, but when I start it outputs Illegal instruction:

# ldc2 app.d
# ./app
Illegal instruction

Here's using the mcpu flag:

# ldc2 --mcpu=i586 app.d -v
binary    /mnt/disc/sdb/part1/program/ldc/1.30/install/bin/ldc2
version   1.30.0-git-32f5a35 (DMD v2.100.1, LLVM 10.0.1)
config    /mnt/disc/sdb/part1/program/ldc/1.30/install/etc/ldc2.conf (i686-pc-linux-gnu)
predefs   LDC all D_Version2 assert D_PreConditions D_PostConditions D_Invariants D_ModuleInfo D_Exceptions D_TypeInfo X86 D_InlineAsm_X86 D_HardFloat LittleEndian D_PIC linux Posix CRuntime_Glibc CppRuntime_Gcc LDC_LLVM_1000
parse     app
importall app
import    object    (/root/usr/program/ldc/1.30/install/include/d/object.d)
import    core.attribute    (/root/usr/program/ldc/1.30/install/include/d/core/attribute.d)
import    ldc.attributes    (/root/usr/program/ldc/1.30/install/include/d/ldc/attributes.d)
import    core.internal.hash    (/root/usr/program/ldc/1.30/install/include/d/core/internal/hash.d)
import    core.internal.traits  (/root/usr/program/ldc/1.30/install/include/d/core/internal/traits.d)
import    core.internal.entrypoint  (/root/usr/program/ldc/1.30/install/include/d/core/internal/entrypoint.d)
import    core.internal.array.appending (/root/usr/program/ldc/1.30/install/include/d/core/internal/array/appending.d)
import    core.internal.array.comparison    (/root/usr/program/ldc/1.30/install/include/d/core/internal/array/comparison.d)
import    core.internal.array.equality  (/root/usr/program/ldc/1.30/install/include/d/core/internal/array/equality.d)
import    core.internal.array.casting   (/root/usr/program/ldc/1.30/install/include/d/core/internal/array/casting.d)
import    core.internal.array.concatenation (/root/usr/program/ldc/1.30/install/include/d/core/internal/array/concatenation.d)
import    core.internal.array.construction  (/root/usr/program/ldc/1.30/install/include/d/core/internal/array/construction.d)
import    core.internal.array.capacity  (/root/usr/program/ldc/1.30/install/include/d/core/internal/array/capacity.d)
import    core.internal.dassert (/root/usr/program/ldc/1.30/install/include/d/core/internal/dassert.d)
import    core.atomic   (/root/usr/program/ldc/1.30/install/include/d/core/atomic.d)
import    core.internal.attributes  (/root/usr/program/ldc/1.30/install/include/d/core/internal/attributes.d)
import    core.internal.atomic  (/root/usr/program/ldc/1.30/install/include/d/core/internal/atomic.d)
import    ldc.intrinsics    (/root/usr/program/ldc/1.30/install/include/d/ldc/intrinsics.di)
import    core.internal.destruction (/root/usr/program/ldc/1.30/install/include/d/core/internal/destruction.d)
import    core.internal.moving  (/root/usr/program/ldc/1.30/install/include/d/core/internal/moving.d)
import    core.internal.postblit    (/root/usr/program/ldc/1.30/install/include/d/core/internal/postblit.d)
import    core.internal.switch_ (/root/usr/program/ldc/1.30/install/include/d/core/internal/switch_.d)
import    core.lifetime (/root/usr/program/ldc/1.30/install/include/d/core/lifetime.d)
import    core.builtins (/root/usr/program/ldc/1.30/install/include/d/core/builtins.d)
semantic  app
entry     main          app.d
semantic2 app
semantic3 app
import    std.stdio (/root/usr/program/ldc/1.30/install/include/d/std/stdio.d)
import    core.stdc.stddef  (/root/usr/program/ldc/1.30/install/include/d/core/stdc/stddef.d)
import    std.algorithm.mutation    (/root/usr/program/ldc/1.30/install/include/d/std/algorithm/mutation.d)
import    std.traits    (/root/usr/program/ldc/1.30/install/include/d/std/traits.d)
import    std.meta  (/root/usr/program/ldc/1.30/install/include/d/std/meta.d)
import    std.range.primitives  (/root/usr/program/ldc/1.30/install/include/d/std/range/primitives.d)
import    std.typecons  (/root/usr/program/ldc/1.30/install/include/d/std/typecons.d)
import    std.format.spec   (/root/usr/program/ldc/1.30/install/include/d/std/format/spec.d)
import    std.format.write  (/root/usr/program/ldc/1.30/install/include/d/std/format/write.d)
import    std.format.internal.write (/root/usr/program/ldc/1.30/install/include/d/std/format/internal/write.d)
import    std.internal.attributes   (/root/usr/program/ldc/1.30/install/include/d/std/internal/attributes.d)
import    std.range (/root/usr/program/ldc/1.30/install/include/d/std/range/package.d)
import    std.array (/root/usr/program/ldc/1.30/install/include/d/std/array.d)
import    std.functional    (/root/usr/program/ldc/1.30/install/include/d/std/functional.d)
import    std.conv  (/root/usr/program/ldc/1.30/install/include/d/std/conv.d)
import    std.ascii (/root/usr/program/ldc/1.30/install/include/d/std/ascii.d)
import    std.range.interfaces  (/root/usr/program/ldc/1.30/install/include/d/std/range/interfaces.d)
import    core.stdc.stdio   (/root/usr/program/ldc/1.30/install/include/d/core/stdc/stdio.d)
import    core.stdc.stdint  (/root/usr/program/ldc/1.30/install/include/d/core/stdc/stdint.d)
import    core.stdc.config  (/root/usr/program/ldc/1.30/install/include/d/core/stdc/config.d)
import    core.stdc.signal  (/root/usr/program/ldc/1.30/install/include/d/core/stdc/signal.d)
import    core.stdc.wchar_  (/root/usr/program/ldc/1.30/install/include/d/core/stdc/wchar_.d)
import    core.stdc.stdarg  (/root/usr/program/ldc/1.30/install/include/d/core/stdc/stdarg.d)
import    core.stdc.time    (/root/usr/program/ldc/1.30/install/include/d/core/stdc/time.d)
import    core.sys.posix.stdc.time  (/root/usr/program/ldc/1.30/install/include/d/core/sys/posix/stdc/time.d)
import    core.sys.posix.sys.types  (/root/usr/program/ldc/1.30/install/include/d/core/sys/posix/sys/types.d)
import    core.sys.posix.config (/root/usr/program/ldc/1.30/install/include/d/core/sys/posix/config.d)
import    core.sys.posix.stdio  (/root/usr/program/ldc/1.30/install/include/d/core/sys/posix/stdio.d)
import    std.exception (/root/usr/program/ldc/1.30/install/include/d/std/exception.d)
import    core.stdc.errno   (/root/usr/program/ldc/1.30/install/include/d/core/stdc/errno.d)
import    std.utf   (/root/usr/program/ldc/1.30/install/include/d/std/utf.d)
import    core.exception    (/root/usr/program/ldc/1.30/install/include/d/core/exception.d)
import    core.internal.string  (/root/usr/program/ldc/1.30/install/include/d/core/internal/string.d)
import    std.algorithm.comparison  (/root/usr/program/ldc/1.30/install/include/d/std/algorithm/comparison.d)
import    core.stdc.string  (/root/usr/program/ldc/1.30/install/include/d/core/stdc/string.d)
import    std.format    (/root/usr/program/ldc/1.30/install/include/d/std/format/package.d)
import    std.format.read   (/root/usr/program/ldc/1.30/install/include/d/std/format/read.d)
import    std.format.internal.read  (/root/usr/program/ldc/1.30/install/include/d/std/format/internal/read.d)
import    std.algorithm.searching   (/root/usr/program/ldc/1.30/install/include/d/std/algorithm/searching.d)
import    std.bitmanip  (/root/usr/program/ldc/1.30/install/include/d/std/bitmanip.d)
import    std.system    (/root/usr/program/ldc/1.30/install/include/d/std/system.d)
import    core.bitop    (/root/usr/program/ldc/1.30/install/include/d/core/bitop.d)
import    core.memory   (/root/usr/program/ldc/1.30/install/include/d/core/memory.d)
import    core.time (/root/usr/program/ldc/1.30/install/include/d/core/time.d)
import    core.sys.posix.time   (/root/usr/program/ldc/1.30/install/include/d/core/sys/posix/time.d)
import    core.sys.posix.signal (/root/usr/program/ldc/1.30/install/include/d/core/sys/posix/signal.d)
import    core.sys.posix.sys.time   (/root/usr/program/ldc/1.30/install/include/d/core/sys/posix/sys/time.d)
import    core.sys.posix.sys.select (/root/usr/program/ldc/1.30/install/include/d/core/sys/posix/sys/select.d)
import    core.sys.linux.sys.time   (/root/usr/program/ldc/1.30/install/include/d/core/sys/linux/sys/time.d)
import    core.sys.linux.config (/root/usr/program/ldc/1.30/install/include/d/core/sys/linux/config.d)
import    core.internal.array.utils (/root/usr/program/ldc/1.30/install/include/d/core/internal/array/utils.d)
import    core.checkedint   (/root/usr/program/ldc/1.30/install/include/d/core/checkedint.d)
import    std.string    (/root/usr/program/ldc/1.30/install/include/d/std/string.d)
import    std.uni   (/root/usr/program/ldc/1.30/install/include/d/std/uni/package.d)
import    std.internal.unicode_tables   (/root/usr/program/ldc/1.30/install/include/d/std/internal/unicode_tables.d)
import    core.internal.lifetime    (/root/usr/program/ldc/1.30/install/include/d/core/internal/lifetime.d)
import    std.format.internal.floats    (/root/usr/program/ldc/1.30/install/include/d/std/format/internal/floats.d)
import    std.math.operations   (/root/usr/program/ldc/1.30/install/include/d/std/math/operations.d)
import    std.math  (/root/usr/program/ldc/1.30/install/include/d/std/math/package.d)
import    std.math.algebraic    (/root/usr/program/ldc/1.30/install/include/d/std/math/algebraic.d)
import    core.math (/root/usr/program/ldc/1.30/install/include/d/core/math.d)
import    core.stdc.math    (/root/usr/program/ldc/1.30/install/include/d/core/stdc/math.d)
import    std.math.constants    (/root/usr/program/ldc/1.30/install/include/d/std/math/constants.d)
import    std.math.exponential  (/root/usr/program/ldc/1.30/install/include/d/std/math/exponential.d)
import    std.math.hardware (/root/usr/program/ldc/1.30/install/include/d/std/math/hardware.d)
import    core.stdc.fenv    (/root/usr/program/ldc/1.30/install/include/d/core/stdc/fenv.d)
import    core.cpuid    (/root/usr/program/ldc/1.30/install/include/d/core/cpuid.d)
import    std.math.remainder    (/root/usr/program/ldc/1.30/install/include/d/std/math/remainder.d)
import    std.math.rounding (/root/usr/program/ldc/1.30/install/include/d/std/math/rounding.d)
import    std.math.traits   (/root/usr/program/ldc/1.30/install/include/d/std/math/traits.d)
import    std.math.trigonometry (/root/usr/program/ldc/1.30/install/include/d/std/math/trigonometry.d)
import    std.internal.unicode_grapheme (/root/usr/program/ldc/1.30/install/include/d/std/internal/unicode_grapheme.d)
GC stats  0M used, 5M free, 5M total
code      app
/root/usr/program/gcc/9.5.0/install/bin/cc app.o -o app -L/root/usr/program/ldc/1.30/install/lib -lphobos2-ldc -ldruntime-ldc -Wl,--gc-sections -lrt -ldl -lpthread -lm -m32

The GCC compiler is built on i686:

# cc --version
cc (GCC) 9.5.0

At first I thought that I needed to rebuild the GCC compiler for the i586 architecture. I downloaded GCC 9.5.0 and started the installation:

# cd source
# ./contrib/download_prerequisites
gmp-6.1.0.tar.bz2: OK
mpfr-3.1.4.tar.bz2: OK
mpc-1.0.3.tar.gz: OK
isl-0.18.tar.bz2: OK
All prerequisites downloaded successfully.
# cd ..
# mkdir build && cd build
# ../source/config.sub i586-linux
i586-pc-linux-gnu
# ../source/configure --prefix=$PWD/../install_i586 --enable-shared --enable-threads=posix --enable-__cxa_atexit --enable-clocale=gnu --enable-languages=c,c++,d --target=i586-pc-linux-gnu --disable-multilib --with-multilib-list=m32
...
# make -j8
...

But during the installation process I got an error:

...
checking for suffix of object files... mv -f .deps/findcomp.Tpo .deps/findcomp.Plo
configure: error: in `/root/source/gcc/9.5.0/build/i586-pc-linux-gnu/libgcc':
configure: error: cannot compute suffix of object files: cannot compile
See `config.log' for more details
Makefile:14150: recipe for target 'configure-target-libgcc' failed
make[1]: *** [configure-target-libgcc] Error 1
make[1]: *** Waiting for unfinished jobs....
...

If I do it without a flag --target=i586-pc-linux-gnu, then everything is assembled without errors.

I'm at a dead end, please help, guys.

On Thursday, 28 July 2022 at 06:01:17 UTC, Alexander Zhirov wrote:

/root/usr/program/gcc/9.5.0/install/bin/cc app.o -o app -L/root/usr/program/ldc/1.30/install/lib -lphobos2-ldc -ldruntime-ldc -Wl,--gc-sections -lrt -ldl -lpthread -lm -m32

Even tried with such a flag separately, it still doesn't work:

# /root/usr/program/gcc/9.5.0/install/bin/cc app.o -o app -L/root/usr/program/ldc/1.30/install/lib -lphobos2-ldc -ldrun
time-ldc -Wl,--gc-sections -lrt -ldl -lpthread -lm -m32 -march=geode
# ./app
Illegal instruction

I also tried with i586 and pentium - the result is the same.

On Thursday, 28 July 2022 at 06:12:49 UTC, Alexander Zhirov wrote:

Pentium Pro and above means at least i686. i586 is Pentium1 which is less featured.
That means that you cant do much, however you can try to tune the i686 target and disable emiting of the instructions that were added from the Pentium Pro. Maybe that the produced instruction will then be compatible.

that would be something like --mcpu=i686 --mattrs=-mmx,-sse and maybe more to be sure.

Other things: "Registered Targets: ... " means that maybe the LDC developers could add the i586 target but did not consider useful to add this is old processor (e.g Pentium1). For that you should ask them if you can and how activate the target when you build ldc2 on your old Geode.

On Thursday, 28 July 2022 at 07:16:13 UTC, user1234 wrote:

ask here https://forum.dlang.org/group/ldc for better answers

On Thursday, 28 July 2022 at 07:16:13 UTC, user1234 wrote:

Fails...

# ldc2 --mcpu=i686 --mattr=-mmx,-sse app.d
# ./app
Illegal instruction

On Thursday, 28 July 2022 at 06:12:49 UTC, Alexander Zhirov wrote:

/root/usr/program/gcc/9.5.0/install/bin/cc app.o -o app -L/root/usr/program/ldc/1.30/install/lib -lphobos2-ldc -ldruntime-ldc -Wl,--gc-sections -lrt -ldl -lpthread -lm -m32

So you eventually built GCC 9.5.0? I have used the

   --with-arch-32=pentium3

option in the configure step for compiling GCC 12.1.0. The build gdc
generates codes which successfully runs on my Pentium III.

On Thursday, 28 July 2022 at 10:26:36 UTC, kdevel wrote:

/root/usr/program/gcc/9.5.0/install/bin/cc app.o -o app -L/root/usr/program/ldc/1.30/install/lib -lphobos2-ldc -ldruntime-ldc -Wl,--gc-sections -lrt -ldl -lpthread -lm -m32

   --with-arch-32=pentium3

I don't understand what I need to do.

On Thursday, 28 July 2022 at 10:26:36 UTC, kdevel wrote:

/root/usr/program/gcc/9.5.0/install/bin/cc app.o -o app -L/root/usr/program/ldc/1.30/install/lib -lphobos2-ldc -ldruntime-ldc -Wl,--gc-sections -lrt -ldl -lpthread -lm -m32

   --with-arch-32=pentium3

The only thing I did (but it still didn't work) was I built a dmd compiler:

root@host ~/program # dmd --version
DMD32 D Compiler v2.100.1-3-g76e3b4137
Copyright (C) 1999-2022 by The D Language Foundation, All Rights Reserved written by Walter Bright

root@host ~/program # dmd -mcpu=native app.d -v
predefs   DigitalMars LittleEndian D_Version2 all Posix ELFv1 linux CRuntime_Glibc CppRuntime_Gcc D_InlineAsm D_InlineAsm_X86 X86 D_PIC assert D_PreConditions D_PostConditions D_Invariants D_ModuleInfo D_Exceptions D_TypeInfo D_HardFloat
binary    dmd
version   v2.100.1-3-g76e3b4137
config    /root/usr/program/dmd/2.100.1/usr/bin/dmd.conf
DFLAGS    -I/root/usr/program/dmd/2.100.1/usr/bin/../include/dmd/druntime/import -I/root/usr/program/dmd/2.100.1/usr/bin/../include/dmd/phobos -L-L/root/usr/program/dmd/2.100.1/usr/bin/../lib -L--export-dynamic -fPIC
parse     app
importall app
import    object    (/root/usr/program/dmd/2.100.1/usr/bin/../include/dmd/druntime/import/object.d)
...
function  std.typecons.Tuple!(uint, "data", uint, "count").Tuple.opCmp!(const(Tuple!(uint, "data", uint, "count"))).opCmp
cc app.o -o app -m32 -Xlinker --export-dynamic -L/root/usr/program/dmd/2.100.1/usr/bin/../lib -Xlinker -Bstatic -lphobos2 -Xlinker -Bdynamic -lpthread -lm -lrt -ldl

root@host ~/program # ./app
Illegal instruction

On Thursday, 28 July 2022 at 10:39:06 UTC, Alexander Zhirov wrote:
[...]

You wrote

At first I thought that I needed to rebuild the GCC compiler for the i586
architecture. I downloaded GCC 9.5.0 and started the installation:

Then you wrote that this process failed. In your next post you quoted some code from the shell:

# /root/usr/program/gcc/9.5.0/install/bin/cc app.o -o app -L/root/usr/program/ldc/1.30/install/lib -lphobos2-ldc -ldrun
time-ldc -Wl,--gc-sections -lrt -ldl -lpthread -lm -m32 -march=geode
# ./app
Illegal instruction

I read this as if you eventually succeeded in compiling your GCC 9.5.0. If you repeat that build but use the switch

--with-arch-32=pentium3

in the configure command your generated GCC 9.5.0 will compile 32-Bit code for the pentium3. I mean instead of

# ../source/configure --prefix=$PWD/../install_i586 --enable-shared --enable-threads=posix --enable-__cxa_atexit --enable-clocale=gnu --enable-languages=c,c++,d --target=i586-pc-linux-gnu --disable-multilib --with-multilib-list=m32

type

# ../source/configure --prefix=$PWD/../install_i586 --enable-shared --enable-threads=posix --enable-__cxa_atexit --enable-clocale=gnu --enable-languages=c,c++,d --target=i586-pc-linux-gnu --disable-multilib --with-multilib-list=m32 --with-arch-32=pentium3

On Thursday, 28 July 2022 at 11:40:09 UTC, kdevel wrote:

At first I thought that I needed to rebuild the GCC compiler for the i586
architecture. I downloaded GCC 9.5.0 and started the installation:

# /root/usr/program/gcc/9.5.0/install/bin/cc app.o -o app -L/root/usr/program/ldc/1.30/install/lib -lphobos2-ldc -ldrun
time-ldc -Wl,--gc-sections -lrt -ldl -lpthread -lm -m32 -march=geode
# ./app
Illegal instruction

--with-arch-32=pentium3

# ../source/configure --prefix=$PWD/../install_i586 --enable-shared --enable-threads=posix --enable-__cxa_atexit --enable-clocale=gnu --enable-languages=c,c++,d --target=i586-pc-linux-gnu --disable-multilib --with-multilib-list=m32

# ../source/configure --prefix=$PWD/../install_i586 --enable-shared --enable-threads=posix --enable-__cxa_atexit --enable-clocale=gnu --enable-languages=c,c++,d --target=i586-pc-linux-gnu --disable-multilib --with-multilib-list=m32 --with-arch-32=pentium3

I have already downloaded the latest GCC sources, nothing compiles anyway. Everything falls on the same error.

checking for suffix of object files... configure: error: in `/home/thinstation/source/gcc/12.1.0/build/i586-pc-linux-gnu/libgcc':
configure: error: cannot compute suffix of object files: cannot compile
See `config.log' for more details
make[1]: *** [Makefile:16026: configure-target-libgcc] Error 1
make[1]: *** Waiting for unfinished jobs....