Re: [Qemu-devel] [PATCH] Add option to disable FDC from ISA bus and ACPI on i386

[Paolo Bonzini]

Il 09/01/2014 22:44, Gabriel L. Somlo ha scritto:
>> (1) Does Mac OS work if you add a _PRS with IRQNoFlags and
>> Memory32Fixed, but leave _CRS as it is?
> 
> Nope, same exact behavior.
> 
>> (2) does it work with -no-hpet?
> 
> With "IRQNoFlags(){2, 8}" hardcoded in HPET._CRS, XP appears to work
> great if -no-hpet is given. I guess _STA evaluates to 0, so nothing
> else matters.

And what about Mac OS X?

>> (3) you could also make that dependent on _OSI("Darwin").
> 
> This works, for the same reason as querying SMC._STA (find something
> "unique" about OS X and conditionally insert IRQNoFlags(){2, 8}) if
> that "something" is detected..
> 
> So, we have two solutions that work:
> 
> 1. hardcode "IRQNoFlags(){2, 8}" and require -no-hpet to prevent XP
>    from bluescreening. Basically, this means we don't support XP on
>    a VM where HPET is enabled.
> 
> 2. conditionally insert "IRQNoFlags(){2, 8}" if _OSI("Darwin") returns
>    0xFFFFFFFF, which is only necessary if we want to run OS X on piix+smp
>    (all other combinations of (piix vs. q35) x (up vs.  smp) work fine
>    already).

_OSI is bad, but (1) is worse.

> I still don't get why on real hardware where the HPET has
> "IRQNoFlags(){2, 8}" in its _CRS method XP seems to be OK...

My laptop has this:

                Device (HPET)
                {
                    Name (_HID, EisaId ("PNP0103"))  // _HID: Hardware ID
                    Method (_STA, 0, NotSerialized)  // _STA: Status
                    {
                        If (LAnd (\WNTF, LNot (\WXPF)))
                        {
                            Return (0x00)
                        }
                        Else
                        {
                            Return (0x0F)
                        }

                        Return (0x00)
                    }

                    Name (BUF0, ResourceTemplate ()
                    {
                        Memory32Fixed (ReadOnly,
                            0xFED00000,         // Address Base
                            0x00000400,         // Address Length
                            _Y27)
                    })
                    Method (_CRS, 0, Serialized)  // _CRS: Current Resource 
Settings
                    {
                        CreateDWordField (BUF0, \_SB.PCI0.LPC.HPET._Y27._BAS, 
HPT0)  // _BAS: Base Address
                        Store (\HPET, HPT0)    // HPET comes from a table that 
BIOS fills in reserved memory
                        Return (BUF0)
                    }
                }

so no IRQs, and my workstation is similar.  They are respectively from
Lenovo and Fujitsu.  Looks like an Apple quirk.

Paolo