Re: Alt SeaBIOS SSDT cpu hotplug

[Avi Kivity <avi@redhat.com>]

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.