Small addition -- apologies for the self-followup:
On 12/05/13 17:12, Laszlo Ersek wrote:
> I tried to trace the problem with ftrace, but I didn't get any mentions of
> em_ret_far(). (Maybe I was looking in the wrong place.)
I applied the following small patch (to the original code):
diff --git a/MdeModulePkg/Universal/Acpi/BootScriptExecutorDxe/X64/S3Asm.S b/MdeModulePkg/Universal/Acpi/BootScriptExecutorDxe/X64/S3Asm.S
index e59fd04..daa4f7e 100644
--- a/MdeModulePkg/Universal/Acpi/BootScriptExecutorDxe/X64/S3Asm.S
+++ b/MdeModulePkg/Universal/Acpi/BootScriptExecutorDxe/X64/S3Asm.S
@@ -18,8 +18,8 @@ ASM_GLOBAL ASM_PFX(AsmTransferControl)
ASM_PFX(AsmTransferControl):
# rcx S3WakingVector :DWORD
# rdx AcpiLowMemoryBase :DWORD
- lea _AsmTransferControl_al_0000(%rip), %eax
- movq $0x2800000000, %r8
+ lea AsmTransferControl(%rip), %eax
+ movq $0x3800000000, %r8
orq %r8, %rax
pushq %rax
shrd $20, %ecx, %ebx
This turns the code right under AsmTransferControl into a working, 64-bit mode
loop. (Recall that 0x38 selects a descriptor that has the L ("64-bitC") bit
set:
> 0x0038: 0x00AF9B000000FFFF: Base=0x00000000 Limit=0xFFFFF Type=0xB (C ER A ) S=0x1 (code/data) DPL=0x0 Present=1 Avail=0 64-bitC=1 D/B=0 LimitGran=0x1 (4KB)
)
While this was spinning (I checked the RIP several times with the qemu monitor
and it was alternating between a few close values -- ie. not stuck), I ran
trace-cmd. The report seems to confirm that the lret is not emulated, because
the only lines I'm seeing are:
qemu-system-x86-3901 [001] 38939.599663: kvm_exit: reason EXTERNAL_INTERRUPT rip 0x9c75be0a info 0 800000ef
qemu-system-x86-3901 [001] 38939.599684: kvm_entry: vcpu 0
repeated infinitely. The rip varies between a few close values,
458 rip 0x9c75be04
313 rip 0x9c75be0a
5 rip 0x9c75be17
4 rip 0x9c75be18
3 rip 0x9c75be22
8 rip 0x9c75be28
Thanks again and sorry for the noise.
Laszlo
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