[Gllug] Debugging kernel loading initrd

[Nix]

On 27 Apr 2008, John Edwards told this:

> The glibc was being built on a i686 CPU with "-march=i486" and
> "-mtune=generic" CFLAGS. I'm currently rebuilding the whole system
> with "--host=i486-pc-linux-gnu" added to glibc configure options to
> see if that helps.

Aha. You can't configure a glibc for specific targets (even specific CPU
submodels like i586) by just setting CFLAGS. glibc's configure script
needs to be told your actual --build system, so that it can look in the
appropriate model-specific sysdeps subdirectories. (You should generally
set that rather than --host if your build system can run binaries
intended for the target glibc, so that it can use it during the build
process.)

When you start building glibc, it says something like

checking sysdep dirs... sysdeps/i386/elf nptl/sysdeps/unix/sysv/linux/i386/i686 nptl/sysdeps/unix/sysv/linux/i386 sysdeps/unix/sysv/linux/i386 nptl/sysdeps/unix/sysv/linux nptl/sysdeps/pthread sysdeps/pthread sysdeps/unix/sysv/linux sysdeps/gnu sysdeps/unix/common sysdeps/unix/mman sysdeps/unix/inet sysdeps/unix/sysv/i386 nptl/sysdeps/unix/sysv sysdeps/unix/sysv sysdeps/unix/i386 nptl/sysdeps/unix sysdeps/unix sysdeps/posix sysdeps/i386/i686/fpu nptl/sysdeps/i386/i686 sysdeps/i386/i686 sysdeps/i386/i486 nptl/sysdeps/i386/i486 sysdeps/i386/fpu nptl/sysdeps/i386 sysdeps/i386 sysdeps/wordsize-32 sysdeps/ieee754/ldbl-96 sysdeps/ieee754/dbl-64 sysdeps/ieee754/flt-32 sysdeps/ieee754 sysdeps/generic/elf sysdeps/generic

See those i686es in there?

If I were to configure it with --build=i586-pc-linux-gnu instead (by
default I pass in --build=i686-pc-linux-gnu on that system), we see

checking sysdep dirs... sysdeps/i386/elf nptl/sysdeps/unix/sysv/linux/i386/i586 nptl/sysdeps/unix/sysv/linux/i386 sysdeps/unix/sysv/linux/i386 nptl/sysdeps/unix/sysv/linux nptl/sysdeps/pthread sysdeps/pthread sysdeps/unix/sysv/linux sysdeps/gnu sysdeps/unix/common sysdeps/unix/mman sysdeps/unix/inet sysdeps/unix/sysv/i386 nptl/sysdeps/unix/sysv sysdeps/unix/sysv sysdeps/unix/i386 nptl/sysdeps/unix sysdeps/unix sysdeps/posix nptl/sysdeps/i386/i586 sysdeps/i386/i586 sysdeps/i386/i486 nptl/sysdeps/i386/i486 sysdeps/i386/fpu nptl/sysdeps/i386 sysdeps/i386 sysdeps/wordsize-32 sysdeps/ieee754/ldbl-96 sysdeps/ieee754/dbl-64 sysdeps/ieee754/flt-32 sysdeps/ieee754 sysdeps/generic/elf sysdeps/generic

Note the differences.

(I submitted an entry to the glibc FAQ explaining this years ago when it
bit me on sparcv9. Ulrich ignored it.)

-- 
`If you are having a "ua luea luea le ua le" kind of day, I can only
 assume that you are doing no work due [to] incapacitating nausea caused 
 by numerous lazy demons.' --- Frossie
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