Re: [Qemu-devel] [PATCH v2] x86: gigabyte alignment for ram

[Gerd Hoffmann <kraxel@redhat.com>]

> 4.1.2.
>  MCFG Table Description
> 
> 
> ...
> 
> If the operating system does not natively comprehend reserving the MMCFG
> region, the MMCFG region must be reserved by firmware. The address range
> reported in the MCFG table or by _CBA method (see Section 4.1.3) must be
> reserved by declaring a motherboard resource.

We don't do this today.

> For most systems, the
> motherboard resource would appear at the root of the ACPI namespace
> (under \_SB) in a node with a _HID of EISAID (PNP0C02), and the
> resources in this case should not be claimed in the root PCI bus’s _CRS.

Which I read as _in case it is at the root of the apci namespace_ it
should not be claimed in PCI0._CRS.  Which makes sense.

My laptop has it reserved in a \_SB\PCI0\LPC\SIO device instead:

            Device (LPC)
            {
                Name (_ADR, 0x001F0000)  // _ADR: Address
                Name (_S3D, 0x03)  // _S3D: S3 Device State
                Name (RID, 0x00)
                Device (SIO)
                {
                    Name (_HID, EisaId ("PNP0C02"))
                    Name (_UID, 0x00)  // _UID: Unique ID
                    Name (SCRS, ResourceTemplate ()
                    {
                        [ ... ]
                        Memory32Fixed (ReadWrite,
                            0xF8000000,         // Address Base
                            0x04000000,         // Address Length
                            )
                        [ ... ]

cheers,
  Gerd