Re: Recent patches break ACPI tables

[luca]

Hi,

Il 18/06/23 22:52, Samuel Thibault ha scritto:
> Hello,
>
> Damien Zammit, le dim. 18 juin 2023 00:48:15 +0000, a ecrit:
> > Almu and I discovered that the following commit breaks --enable-apic 
> > --enable-ncpus= >1 --disable-linux-groups
> >    
> > * d972c01c pmap: only map lower BIOS memory 1:1 when using Linux drivers
> >
> > I believe the ACPI tables need temporary low memory mapping to access them.
>
> Luca, what do you think?
>
> Can we perhaps fix the ACPI code to use phystokv to translate from
> physical addresses to virtual addresses?

yes that's probably the best way to fix the code.

By the way, how, is it exactly crashing? It might not be related to 
ACPI/APIC code, I tried a simple program on a 32-bit kernel with 
--enable-apic but without --enable-ncpus and it seems to work. If I use 
--enable-ncpus=2 it seems to fail quite early, even without -smp=2 in 
qemu. At the moment I'm not able to set a breakpoint even to the C entry 
point, I'm not sure why, I think I did it in the past.

Maybe there is some other part, SMP_specific, that assumes the lower 
memory is mapped 1:1? I remember there was some bootstrap code to start 
the secondary cpus, but I don't remember the details.


Luca