Re: ACPI endianness

["Philippe Mathieu-Daudé" <philmd@redhat.com>]

On 10/10/21 15:24, BALATON Zoltan wrote:
> Hello,
> 
> I'm trying to fix shutdown and reboot on pegasos2 which uses ACPI as
> part of the VIA VT8231 (similar to and modelled in hw/isa/vt82c686b.c)
> and found that the guest writes to ACPI PM1aCNT register come out with
> wrong endianness but not shure why. I have this:
> 
> $ qemu-system-ppc -M pegasos2 -monitor stdio
> (qemu) info mtree
> [...]
> memory-region: pci1-io
>   0000000000000000-000000000000ffff (prio 0, i/o): pci1-io
> [...]
>     0000000000000f00-0000000000000f7f (prio 0, i/o): via-pm
>       0000000000000f00-0000000000000f03 (prio 0, i/o): acpi-evt
>       0000000000000f04-0000000000000f05 (prio 0, i/o): acpi-cnt
>       0000000000000f08-0000000000000f0b (prio 0, i/o): acpi-tmr
> 
> memory-region: system
>   0000000000000000-ffffffffffffffff (prio 0, i/o): system
>     0000000000000000-000000001fffffff (prio 0, ram): pegasos2.ram
>     0000000080000000-00000000bfffffff (prio 0, i/o): alias pci1-mem0-win
> @pci1-mem 0000000080000000-00000000bfffffff
>     00000000c0000000-00000000dfffffff (prio 0, i/o): alias pci0-mem0-win
> @pci0-mem 00000000c0000000-00000000dfffffff
>     00000000f1000000-00000000f100ffff (prio 0, i/o): mv64361
>     00000000f8000000-00000000f8ffffff (prio 0, i/o): alias pci0-io-win
> @pci0-io 0000000000000000-0000000000ffffff
>     00000000f9000000-00000000f9ffffff (prio 0, i/o): alias pci0-mem1-win
> @pci0-mem 0000000000000000-0000000000ffffff
>     00000000fd000000-00000000fdffffff (prio 0, i/o): alias pci1-mem1-win
> @pci1-mem 0000000000000000-0000000000ffffff
>     00000000fe000000-00000000feffffff (prio 0, i/o): alias pci1-io-win
> @pci1-io 0000000000000000-0000000000ffffff
>     00000000ff800000-00000000ffffffff (prio 0, i/o): alias pci1-mem3-win
> @pci1-mem 00000000ff800000-00000000ffffffff
>     00000000fff00000-00000000fff7ffff (prio 0, rom): pegasos2.rom
> 
> The guest (which is big endian PPC and I think wotks on real hardware)
> writes to 0xf05 in the io region which should be the high byte of the
> little endian register but in the acpi code it comes out wrong, instead
> of 0x2800 I get in acpi_pm1_cnt_write: val=0x28

Looks like a northbridge issue (MV64340).
Does Pegasos2 enables bus swapping?
See hw/pci-host/mv64361.c:585:

static void warn_swap_bit(uint64_t val)
{
    if ((val & 0x3000000ULL) >> 24 != 1) {
        qemu_log_mask(LOG_UNIMP, "%s: Data swap not implemented", __func__);
    }
}