Boot problem

Jonathan-Marc Lapointe jmlap75 at yahoo.ca
Mon Jan 26 07:59:50 PST 2004


Thanx to all of you, I'll take a look to the crosscompilation hint.

Thanx again

Jonathan


Ronald Hummelink wrote:
> On Mon, 2004-01-26 at 12:01, Greg Schafer wrote:
> 
>>On Mon, Jan 26, 2004 at 11:42:58AM +0100, Meher Khiari wrote:
>>
>>>>Huh? It's the kernel crapping out and not the compiled LFS.
>>>>As you quite
>>>>rightly say, the K6 is more like an i586. Compiling his
>>>>kernel for i586
>>>>should allow it to boot fine.
>>>
>>>No, it is more an LFS compilation pb.
>>>Effectively the K6 is a i586 and when you compiled the packages for the
>>>Athlon platform it was compiled for the i686. You have compiled the kernel
>>>for the i586 (and it works) but the other binaries (bash, init ....) are
>>>compiled for an i686 and that's why it don't work !
>>>
>>>
>>>>There is no need for cross-compiling hint unless _optimizing_
>>>>for a lesser
>>>>cpu. By default, i.e. without any sort of CFLAGS, gcc will emit i386
>>>>instructions that run on all x86 CPU's (equivalent to -march=i386).
>>>
>>>By default the configure script tries to figure out the machine type and
>>>emits i686 for the Athlon and compiles for it !!
>>
>>No, you're completely wrong on both counts. This has been explained on the
>>lists hundreds of times. GCC will *schedule* for the i686. But the
>>instructions will still run on all x86 CPU's. The OP's problem is the kernel
>>which WAS compiled with -march=1686 or -march=athlon depending on what
>>CPU was selected thus causing the blowup. That's why recompiling for i586
>>will make it boot.
>>
> 
> 
> Greg calm down!
> 
> The very next thing that should be displayed is the message displayed by
> init. since this does not happen, the problem is init, not the kernel.
> This behaviour is HIGHLY typical for the build on fast can not run on
> slow box. Having experienced this personally i know what the behaviour
> looks like. The fact the system does boot on teh athlon only strengtens
> the suspect is indeed Illegal instruction while running init... My
> Lfs-3.1-cvs box suffered this very same path.
> 
> A kernel build for i686 will reboot instantly when booted on i586, not
> somewhere along the way (there is detection code very early in
> kernelboot)
> 
> (So yes, I DARE to tell YOU you are wrong since every symptom points
> that way.)
> 
> Solution is indeed as suggested: get the crosscompiling hint, build the
> i586 faker module, rebuild lfs from scratch.
> 
> Ronald
> 
> 
> 
>>If you don't believe me. Try this:
>>
>>echo 'main(){}' > dummy.c
>>gcc -fverbose-asm -S dummy.c
>>grep march dummy.s
>>
>>and tell me what you see? I dare you to still tell me I'm wrong!
> 
> 
>>Greg
>>LFS Toolchain Maintainer
> 




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