[SeaBIOS] Alt SeaBIOS SSDT cpu hotplug
Avi Kivity
avi at redhat.com
Wed Jul 7 12:07:21 CEST 2010
On 07/07/2010 07:57 AM, Kevin O'Connor wrote:
> Hi,
>
> I've been playing with the cpu hotplug SSDT changes. Attached is a
> proposal for an alternative method of adding ACPI support.
>
> The idea is to continue to build a dynamic SSDT based on CountCPUs and
> MaxCountCPUs. The dynamic SSDT entries just call methods in the main
> DSDT.
>
> This is completely untested. Hopefully the patch will demonstrate the
> idea though.
>
> The objective is to dynamically build an SSDT that looks something
> like:
>
> ===========================================================
> {
> Scope (_SB) {
> External(CPMA, MethodObj)
> External(CPST, MethodObj)
> External(CPEJ, MethodObj)
> #define DefCPU(nr) \
> Processor (CP##nr, 0x##nr, 0x0000b010, 0x06) { \
> Name (_HID, "ACPI0007") \
> Name (ID, 0x##nr) \
> Method(_MAT, 0) { \
> Return(CPMA(ID)) \
> } \
> Method (_STA) { \
> Return(CPST(ID)) \
> } \
> Method (_EJ0, 1, NotSerialized) { \
> Return(CPEJ(ID, Arg0)) \
> } \
> }
> DefCPU(00)
> DefCPU(01)
> DefCPU(02)
> DefCPU(03)
> DefCPU(AA)
> Name(CPUS, Package() {
> CP00, CP01, CP02, CP03, CPAA,
> })
> Name(CPON, Package() {
> One, One, One, Zero, Zero
> })
> }
> }
> ===========================================================
>
> with a dynamic number of cpus.
>
> The "CPUS" package stores references to the Processor objects, and the
> "CPON" package stores the state of which cpus are active. With this
> info, hopefully there is no need to update the MADT tables.
>
> Thoughts?
>
Very nice. I thought about doing this but abandoned it as
unmaintainable. Using external functions and the ID variable, however,
reduces the mess to tolerable proportions, and gains us a lot of
flexibility. We can now have any combinations of sockets and installed
cpus.
--
I have a truly marvellous patch that fixes the bug which this
signature is too narrow to contain.
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