Re: [edk2-devel] [PATCH V2] UefiCpuPkg/CpuDxe: Fix boot error

["Guo Dong" <guo.dong@intel.com>]

Thanks Tom to help verify this change and point out an extra comma after rcx.
I will remove that extra comma when pushing this patch.
I could send V3 patch if required to remove this extra comma.

Thanks,
Guo

> -----Original Message-----
> From: devel@edk2.groups.io <devel@edk2.groups.io> On Behalf Of Lendacky,
> Thomas
> Sent: Thursday, January 7, 2021 8:02 AM
> To: devel@edk2.groups.io; Dong, Guo <guo.dong@intel.com>
> Cc: Dong, Eric <eric.dong@intel.com>; Ni, Ray <ray.ni@intel.com>;
> lersek@redhat.com; Kumar, Rahul1 <rahul1.kumar@intel.com>
> Subject: Re: [edk2-devel] [PATCH V2] UefiCpuPkg/CpuDxe: Fix boot error
> 
> On 1/6/21 9:10 PM, Guo Dong via groups.io wrote:
> > REF: https://bugzilla.tianocore.org/show_bug.cgi?id=3084
> >
> > When DXE drivers are dispatched above 4GB memory in 64bit
> > mode, the address setCodeSelectorLongJump in stack will
> > be override by parameter. Jump to Qword is not supported
> > by some processors. So use "o64 retf" instead.
> >
> > Signed-off-by: Guo Dong <guo.dong@intel.com>
> 
> With one little comment below, I verified this method allows my system to
> boot.
> 
> Tested-by: Tom Lendacky <thomas.lendacky@amd.com>
> 
> > ---
> >   UefiCpuPkg/CpuDxe/X64/CpuAsm.nasm | 8 +++-----
> >   1 file changed, 3 insertions(+), 5 deletions(-)
> >
> > diff --git a/UefiCpuPkg/CpuDxe/X64/CpuAsm.nasm
> b/UefiCpuPkg/CpuDxe/X64/CpuAsm.nasm
> > index c3489bcc3e..a8216cd56f 100644
> > --- a/UefiCpuPkg/CpuDxe/X64/CpuAsm.nasm
> > +++ b/UefiCpuPkg/CpuDxe/X64/CpuAsm.nasm
> > @@ -20,13 +20,11 @@
> >   ;------------------------------------------------------------------------------
> >   global ASM_PFX(SetCodeSelector)
> >   ASM_PFX(SetCodeSelector):
> > -    sub     rsp, 0x10
> > +    push    rcx,
> 
> Extraneous comma after rcx.
> 
> Thanks,
> Tom
> 
> >       lea     rax, [setCodeSelectorLongJump]
> > -    mov     [rsp], rax
> > -    mov     [rsp+4], cx
> > -    jmp     dword far [rsp]
> > +    push    rax
> > +    o64 retf
> >   setCodeSelectorLongJump:
> > -    add     rsp, 0x10
> >       ret
> >
> >   ;------------------------------------------------------------------------------
> >
> 
> 
> 
>