B580 on POWER9: Unable to handle kernel data access on read at 0xc00a0000000003cc

[Simon Richter]

Hi,

> Hi Simon, thanks for reporting this. Could you please report this to our gitlab
> issues so we ensure this doesn't get lost on this busy mailing list?

I've added it to

     https://gitlab.freedesktop.org/drm/xe/kernel/-/issues/1824

which is the same problem on aarch64.

I don't think this is a porting issue, just that the ports are more 
likely to have either something else or nothing at all at the ISA VGA 
addresses, and are thus more likely to trip up, but this would also 
affect PCs that have a different primary VGA device (BMC, onboard, 
multiple GPUs).

This seems to be some bug workaround for VGA emulation mode, so I don't 
know whether it's safe to just remove it when the card is not mapped to 
VGA ports (that would be somewhat easy to do), when the expansion ROM is 
disabled (even easier to do), or if another mechanism is needed.

> Since you are building your own kernel. Would you mind trying to reproduce
> with latest drm-tip branch from https://gitlab.freedesktop.org/drm/tip

Same behaviour, added the log to the bug as well.

    Simon