Re: [PATCH 1/4] OvmfPkg/Sec/Ia32: free up EAX for other uses while setting up the stack

[Jordan Justen <jordan.l.justen@intel.com>]

On 2017-11-10 07:49:05, Laszlo Ersek wrote:
> Currently EAX is used as an intermediary in setting ESP to
> SEC_TOP_OF_STACK, and in passing SEC_TOP_OF_STACK to
> SecCoreStartupWithStack() as the "TopOfCurrentStack" argument.
> 
> In a later patch we'll use EAX differently, so replace it with EBX under
> the current use.
> 
> Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
> Cc: Jordan Justen <jordan.l.justen@intel.com>
> Cc: Ruiyu Ni <ruiyu.ni@intel.com>
> Contributed-under: TianoCore Contribution Agreement 1.1
> Signed-off-by: Laszlo Ersek <lersek@redhat.com>
> ---
>  OvmfPkg/Sec/Ia32/SecEntry.nasm | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/OvmfPkg/Sec/Ia32/SecEntry.nasm b/OvmfPkg/Sec/Ia32/SecEntry.nasm
> index 7fee1c2b2e4f..54d074e621f6 100644
> --- a/OvmfPkg/Sec/Ia32/SecEntry.nasm
> +++ b/OvmfPkg/Sec/Ia32/SecEntry.nasm
> @@ -40,8 +40,8 @@ ASM_PFX(_ModuleEntryPoint):
>      ;
>      %define SEC_TOP_OF_STACK (FixedPcdGet32 (PcdOvmfSecPeiTempRamBase) + \
>                            FixedPcdGet32 (PcdOvmfSecPeiTempRamSize))
> -    mov     eax, SEC_TOP_OF_STACK
> -    mov     esp, eax
> +    mov     ebx, SEC_TOP_OF_STACK
> +    mov     esp, ebx

Can't you initialize the temp RAM before this code?

-Jordan