On Fri, 2014-09-26 at 11:57 -0700, Jordan Justen wrote:
> On 2014-09-26 03:38:53, Chen Fan wrote:
> > Due to AP cannot invoke any EFI API to allocate stack
> > memory region. so BSP needs to know the APs amount and
> > then could allocate stack spaces for them.
> >
> > Contributed-under: TianoCore Contribution Agreement 1.0
> > Signed-off-by: Chen Fan <[email protected]>
> > ---
> > UefiCpuPkg/CpuDxe/CpuMp.c | 20 ++++++++++++++++++--
> > 1 file changed, 18 insertions(+), 2 deletions(-)
> >
> > diff --git a/UefiCpuPkg/CpuDxe/CpuMp.c b/UefiCpuPkg/CpuDxe/CpuMp.c
> > index 8cf711a..2d52b22 100644
> > --- a/UefiCpuPkg/CpuDxe/CpuMp.c
> > +++ b/UefiCpuPkg/CpuDxe/CpuMp.c
> > @@ -18,9 +18,10 @@
> > VOID *mCommonStack = 0;
> > VOID *mTopOfApCommonStack = 0;
> >
> > +volatile UINTN mNumberOfProcessors;
> >
> > /**
> > - Application Processor C code entry point
> > + Application Processor C code entry point.
>
> This should be done in the original patch that adds it. I updated it
> on the ap-startup-example branch.
OK, I will rework based on your branch.
>
> > **/
> > VOID
> > @@ -29,11 +30,19 @@ ApEntryPointInC (
> > VOID
> > )
> > {
> > + //
> > + // AP initialization C code
> > + //
> > + mNumberOfProcessors++;
> > +
> > + AsmApDoneWithCommonStack ();
>
> This is not quite safe, since the AP is actually still using the
> stack.
>
> Instead, can you add a new PCD, PcdCpuMaxLogicalProcessorNumber, with
> a default of 64?
>
> The BSP should allocate PcdCpuMaxLogicalProcessorNumber *
> PcdCpuApStackSize before starting the APs.
>
> In ApEntryPointInC, the AP can take a part of this buffer and use
> BaseLib:SwitchStacks to stop using the common stack, and start running
> a new function.
>
> This should also remove the need to update the assembly code beyond
> what I provided. I really prefer to minimize assembly code, because it
> is a frustrating extra maintenence burden.
Ok, got it.
I will change my implementation and use PCD pre-allocated APs stack
buffer.
Thanks,
Chen
>
> -Jordan
>
> > +
> > + CpuSleep ();
> > }
> >
> >
> > /**
> > - Initialize Multi-processor support
> > + Initialize Multi-processor support.
> >
> > **/
> > VOID
> > @@ -41,5 +50,12 @@ InitializeMpSupport (
> > VOID
> > )
> > {
> > + mNumberOfProcessors = 1;
> > +
> > + if (mNumberOfProcessors == 1) {
> > + return;
> > + }
> > +
> > + DEBUG ((DEBUG_INFO, "Detect CPU count: %d\n", mNumberOfProcessors));
> > }
> >
> > --
> > 1.9.3
> >
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