On Mon, Jul 13, 2020 at 10:20:12AM +0300, Michael Tokarev wrote: > 12.07.2020 15:00, Simon John wrote: > > macos guests no longer boot after commit > > 5d971f9e672507210e77d020d89e0e89165c8fc9 > > > > acpi-tmr needs 2 byte memory accesses, so breaks as that commit only allows > > 4 bytes. > > > > Fixes: 5d971f9e672507210e7 (memory: Revert "memory: accept mismatching > > sizes in memory_region_access_valid") > > Buglink: https://bugs.launchpad.net/qemu/+bug/1886318 > > Actually this fixes 77d58b1e47c8d1c661f98f12b47ab519d3561488 > Author: Gerd Hoffmann <kra...@redhat.com> > Date: Thu Nov 22 12:12:30 2012 +0100 > Subject: apci: switch timer to memory api > Signed-off-by: Gerd Hoffmann <kra...@redhat.com> > > because this is the commit which put min_access_size = 4 in there > (5d971f9e672507210e7 is just a messenger, actual error were here > earlier but it went unnoticed). > > While min_access_size=4 was most likely an error, I wonder why > we use 1 now, while the subject says it needs 2? What real min > size is here for ACPI PM timer? > > /mjt
Well the ACPI spec 1.0b says 4.7.3.3 Power Management Timer (PM_TMR) ... This register is accessed as 32 bits. and this text is still there in 6.2. So it's probably worth it to cite this in the commit log and explain it's a spec violation. I think it's better to be restrictive and only allow the minimal variation from spec - in this case I guess this means 2 byte reads. In any case pls do include an explanation for why you picked one over the other. > > > Signed-off-by: Simon John <g...@the-jedi.co.uk> > > --- > > Â hw/acpi/core.c | 2 +- > > Â 1 file changed, 1 insertion(+), 1 deletion(-) > > > > diff --git a/hw/acpi/core.c b/hw/acpi/core.c > > index f6d9ec4f13..05ff29b9d7 100644 > > --- a/hw/acpi/core.c > > +++ b/hw/acpi/core.c > > @@ -527,7 +527,7 @@ static void acpi_pm_tmr_write(void *opaque, hwaddr > > addr, uint64_t val, > > Â static const MemoryRegionOps acpi_pm_tmr_ops = { > > Â Â Â Â .read = acpi_pm_tmr_read, > > Â Â Â Â .write = acpi_pm_tmr_write, > > -Â Â Â .valid.min_access_size = 4, > > +Â Â Â .valid.min_access_size = 1, > > Â Â Â Â .valid.max_access_size = 4, > > Â Â Â Â .endianness = DEVICE_LITTLE_ENDIAN, > > Â };