Re: Anybody got 2.4.0 running on a 386 ?

[Robert Kaiser <rob@sysgo.de>]

On Die, 09 Jan 2001 you wrote:
> Robert Kaiser wrote:
> > 
> > On Die, 09 Jan 2001 you wrote:
> > > Robert Kaiser wrote:
> > > > I can't seem to get the new 2.4.0 kernel running on a 386 CPU.
> > > > The kernel was built for a 386 Processor, Math emulation has been enabled.
> > > > I tried three different 386 boards. Execution seems to get as far as
> > > > pagetable_init() in arch/i386/mm/init.c, then it falls back into the BIOS as
> > > > if someone had pressed the reset button. The same kernel boots fine on
> > > > 486 and Pentium Systems.
> >  ..... The last thing I see is
> > "Uncompressing Linux... Ok, booting the kernel." I have added some
> > quick and dirty debug code that writes messages directly to the VGA
> > screen buffer. According to that, execution seems to get as far as the
> > statement
> > 
> >         *pte = mk_pte_phys(__pa(vaddr), PAGE_KERNEL);
> > 
> 
> Could it be possible that memory size is being misdetected?  Try mem=8M
> (or less) on the command line.  Try to catch the value of pte when it
> crashes.

I tried "mem=4M" -- no effect. The value of pte is 0xc0001000, so it seems
to be the first invocation of that statement in the for() loop.

Now comes the amazing (to me) part: I split the above statement up into:

	temp = mk_pte_phys(__pa(vaddr), PAGE_KERNEL);
	*pte = temp;

where temp is declared "volatile pte_t". I inserted test-prints between the
above two lines. Accoding to that, the _first_ line , i.e. the evaluation of the
mk_pte_phys() macro is causing the crash!

I am still trying to figure out what mk_pte_phys() does. Apparently it involves
an access to the kernel's data section. My current guess is that the data
section is not correctly mapped at this point. Would that be possible ?



----------------------------------------------------------------
Robert Kaiser                         email: rkaiser@sysgo.de
SYSGO RTS GmbH
Am Pfaffenstein 14                    phone: (49) 6136 9948-762
D-55270 Klein-Winternheim / Germany   fax:   (49) 6136 9948-10
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