On Sun, May 23, 2021 at 07:09:26PM +0200, BALATON Zoltan wrote:
On Sun, 23 May 2021, BALATON Zoltan wrote:
On Sun, 23 May 2021, Alexey Kardashevskiy wrote:
One thing to note about PCI is that normally I think the client
expects the firmware to do PCI probing and SLOF does it. But VOF
does not and Linux scans PCI bus(es) itself. Might be a problem for
you kernel.
I'm not sure what info does MorphOS get from the device tree and what it
probes itself but I think it may at least need device ids and info about
the PCI bus to be able to access the config regs, after that it should
set the devices up hopefully. I could add these from the board code to
device tree so VOF does not need to do anything about it. However I'm
not getting to that point yet because it crashes on something that it's
missing and couldn't yet find out what is that.
I'd like to get Linux working now as that would be enough to test this
and then if for MorphOS we still need a ROM it's not a problem if at
least we can boot Linux without the original firmware. But I can't make
Linux open a serial console and I don't know what it needs for that. Do
you happen to know? I've looked at the sources in Linux/arch/powerpc but
not sure how it would find and open a serial port on pegasos2. It seems
to work with the board firmware and now I can get it to boot with VOF
but then it does not open serial so it probably needs something in the
device tree or expects the firmware to set something up that we should
add in pegasos2.c when using VOF.
I've now found that Linux uses rtas methods read-pci-config and
write-pci-config for PCI access on pegasos2 so this means that we'll
probably need rtas too (I hoped we could get away without it if it were only
used for shutdown/reboot or so but seems Linux needs it for PCI as well and
does not scan the bus and won't find some devices without it).
Yes, definitely sounds like you'll need an RTAS implementation.
While VOF can do rtas, this causes a problem with the hypercall method using
sc 1 that goes through vhyp but trips the assert in ppc_store_sdr1() so
cannot work after guest is past quiesce.
So the question is why is that
assert there
Ah.. right. So, vhyp was designed for the PAPR use case, where we
want to model the CPU when it's in supervisor and user mode, but not
when it's in hypervisor mode. We want qemu to mimic the behaviour of
the hypervisor, rather than attempting to actually execute hypervisor
code in the virtual CPU.
On systems that have a hypervisor mode, SDR1 is hypervisor privileged,
so it makes no sense for the guest to attempt to set it. That should
be caught by the general SPR code and turned into a 0x700, hence the
assert() if we somehow reach ppc_store_sdr1().