Re: Problems with irq mapping in qemu v5.2

[BALATON Zoltan]

On Tue, 22 Dec 2020, Guenter Roeck wrote:
> On 12/22/20 2:57 PM, BALATON Zoltan wrote:
>
> [ ... ]
>
> > I've already forgot about the details but we have analysed it quite throughly 
> > back when the via ide changes were made. Here are some random pointers to 
> > threads that could have some info:
> > This was the final solution that was merged as the simplest that worked for all 
> > cases we've tried to fix:
> > https://lists.nongnu.org/archive/html/qemu-devel/2020-03/msg03977.html
> This set of patches is in v5.2, yet I can still not instantiate an IDE drive, 
> at least
> not with "-drive file=<filename>,if=ide". Is there some other means to 
> instantiate
> an ide drive with the fuloong2e emulation ?
>
> For reference, here is my qemu command line:
>
> qemu-system-mips64el -M fulong2e \
>    -kernel vmlinux -no-reboot -m 256 \
>    -snapshot -drive file=rootfs.mipsel.ext3,format=raw,if=ide \
>    -vga none \
>    --append "root=/dev/sda console=ttyS0" \
>    -nographic -serial stdio -monitor none

This is what worked the last time we've tried:

https://lists.nongnu.org/archive/html/qemu-devel/2020-03/msg04086.html

and this was my understanding of the issues with this VIA IDE function of 
these integrated southbridge/superio chips and Linux's approach to them 
that may be relevant to debug this:

https://lists.nongnu.org/archive/html/qemu-devel/2020-03/msg00019.html

We've found that pegasos2 PPC board uses this "half-native" mode where 
IRQs are using ISA IRQs but not sure what the fuloong2e has. Linux did not 
seem to care as long as there's no mismatch between config bits and IRQ 
routing. Although we've also found some comments in Linux may be 
misleading:

https://lists.nongnu.org/archive/html/qemu-devel/2020-03/msg02349.html

For the command line I never know which of these work for which machines 
so I just avoid using -drive if=... If the machine has 4 IDE ports then 
-hda -hdb -cdrom usually works, otherwise the most verbose form should 
always work which is:

-drive if=none,id=cd,file=some.iso,format=raw \
-device ide-cd,drive=cd,bus=ide.1

and similar for HD image with ide-hd and bus=ide.0 or wherever you want to 
connect it.

Regards,
BALATON Zoltan