Re: [PATCH] target/ppc: Fix e6500 boot

[Cédric Le Goater]

On 12/25/21 22:53, BALATON Zoltan wrote:
> On Sat, 25 Dec 2021, mario@locati.it wrote:
> > I have tried to launch a freshly compiled qemu from git master on a NXP 
> > T2080RDB devkit that has a e6500 CPU in combination with a freshly compiled 
> > kernel 5.16-rc6
> > I have Debian SID ppc64 up and running using such a kernel, and when I launch 
> > qemu to run a VM with the same debian sid for ppc64 and the same kernel using 
> > --enable-kvm I end up with a kernel panic

Thanks for testing,

> > [....]
> > Run /sbin/init as init process
> > random: fast init done
> > systemd[1]: illegal instruction (4) at 3fff96562ac8 nip 3fff96562ac8 lr 
> > 3fff96562aa8 code 1 in libc-2.32.so[3fff96516000+1f7000]

debian ppc64 sid has a glibc 2.33 AFAICT

> > systemd[1]: code: 60000000 38600006 9122b7e8 4801bead 60000000 60000000 
> > 8122b7e8 2c090004
> > systemd[1]: code: 40820014 39200005 60000000 9122b7e8 <00000000> 60000000 
> > 8122b7e8 2c090005
>
> Looks like it trips on a 0 opcode here in the middle of other values that look like valid code so I wonder how that 0 got there? Did something overwrite it before it tried to execute it? 

This looks like the abort() routine.

> If it always happens on the same address maybe you could try attaching gdb and 
> put a watch point on that address to see what writes there, otherwise I don't 
> know how to debug this.

Could you deduce the routine name from the nip ?

Thanks,

C.