Re: Anybody got 2.4.0 running on a 386 ?

Robert Kaiser
2001-01-10T00:05:00Z

On Die, 09 Jan 2001 you wrote:
> On Tue, 9 Jan 2001, Robert Kaiser wrote:
>
> > Now comes the amazing (to me) part: I split the above statement up into:
> >
> > temp = mk_pte_phys(__pa(vaddr), PAGE_KERNEL);
> > *pte = temp;
>
> this is almost impossible (except some really weird compiler bug) - unless
> the mem_map address is invalid. This could happen if your kernel image is
> *just* too large. Do things improve if you disable eg. ext2fs support (i
> know, but should be enough to boot).

Sorry, no ext2fs in this kernel (it is for a diskless embedded system). I seem
to recall though that the problem at one point magically went away when I
disabled the FPU emulation, but I have not been able to reproduce this
recently, so I'm not sure. Making minor changes to the kernel code (such as
adding/removing some test-prints) certainly does not affect the behavior.

> Or if that part is not mapped
> correctly (which does happen sometimes as well).

What could I do to check/fix this ?

>
> and are you sure it crashes there? [are you putting delays between your
> printouts?]

I have put a "halting statement" (i.e. "while(1);") after my printouts to make
sure execution does not go any further than that point. I moved this halting
statement ahead in the code line by line until the crash would occur again.
So, yes, I am pretty sure.

>
> > 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!
>
> it accesses mem_map variable, which is near to the end of the kernel
> image, so it could indeed something of that sort. An uncompressed kernel
> image (including the data area) must not be bigger than 4MB (IIRC).

According to my System.map file, mem_map is at 0xc0244f78. Does that help ?

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Robert Kaiser email: rkaiser@sysgo.de
SYSGO RTS GmbH
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