On 12/05/13 18:42, Paolo Bonzini wrote: > diff --git a/MdeModulePkg/Universal/Acpi/BootScriptExecutorDxe/X64/S3Asm.S > b/MdeModulePkg/Universal/Acpi/BootScriptExecutorDxe/X64/S3Asm.S > index e59fd04..d1cac9d 100644 > --- a/MdeModulePkg/Universal/Acpi/BootScriptExecutorDxe/X64/S3Asm.S > +++ b/MdeModulePkg/Universal/Acpi/BootScriptExecutorDxe/X64/S3Asm.S > @@ -19,7 +19,7 @@ ASM_PFX(AsmTransferControl): > # rcx S3WakingVector :DWORD > # rdx AcpiLowMemoryBase :DWORD > lea _AsmTransferControl_al_0000(%rip), %eax > - movq $0x2800000000, %r8 > + movq $0x1000000000, %r8 > orq %r8, %rax > pushq %rax > shrd $20, %ecx, %ebx > @@ -28,24 +28,32 @@ ASM_PFX(AsmTransferControl): > movl %ebx, jmp_addr(%rip) > lret > _AsmTransferControl_al_0000: > + # Old SS should still be okay? > + addl _AsmTransferControl_al_0001-_AsmTransferControl_al_0000, %eax > + pushl $0x28 > + pushl %eax > + movq %cr0, %rax > + movq %cr4, %rbx > + andl $0x7fffffff, %eax > + andb $0xdf, %bl > + movq %rax, %cr0 # sets EFER.LMA=0 too, so says Intel > + movl $0x0c0000080, %ecx > + rdmsr > + andb $0xfe, %ah # set EFER.LME=0 > + wrmsr > + movq %rbx, %cr4 # only now set CR4.PAE=0 > + lret > +_AsmTransferControl_al_0001: > .byte 0x0b8, 0x30, 0 # mov ax, 30h as selector > movl %eax, %ds > movl %eax, %es > movl %eax, %fs > movl %eax, %gs > movl %eax, %ss > - movq %cr0, %rax > - movq %cr4, %rbx > - .byte 0x66 > - andl $0x7ffffffe, %eax > - andb $0xdf, %bl > - movq %rax, %cr0 > - .byte 0x66 > - movl $0x0c0000080, %ecx > - rdmsr > - andb $0xfe, %ah > - wrmsr > - movq %rbx, %cr4 > + movl %cr0, %rax # Get control register 0 > + .byte 0x66 > + .byte 0x83,0xe0,0xfe # and eax, 0fffffffeh ; Clear PE bit (bit #0) > + .byte 0xf,0x22,0xc0 # mov cr0, eax ; Activate real mode
I had to add this incremental patch to get it to compile: diff --git a/MdeModulePkg/Universal/Acpi/BootScriptExecutorDxe/X64/S3Asm.S b/MdeModulePkg/Universal/Acpi/BootScriptExecutorDxe/X64/S3Asm.S index c28df3f..85d2a36 100644 --- a/MdeModulePkg/Universal/Acpi/BootScriptExecutorDxe/X64/S3Asm.S +++ b/MdeModulePkg/Universal/Acpi/BootScriptExecutorDxe/X64/S3Asm.S @@ -30,8 +30,8 @@ ASM_PFX(AsmTransferControl): _AsmTransferControl_al_0000: # Old SS should still be okay? addl _AsmTransferControl_al_0001-_AsmTransferControl_al_0000, %eax - pushl $0x28 - pushl %eax + .byte 0x6a,0x28 # pushl $0x28 ; opnd sz = 32bits in seg 0x10 + .byte 0x50 # pushl %eax movq %cr0, %rax movq %cr4, %rbx andl $0x7fffffff, %eax @@ -50,7 +50,7 @@ _AsmTransferControl_al_0001: movl %eax, %fs movl %eax, %gs movl %eax, %ss - movl %cr0, %rax # Get control register 0 + .byte 0x0f,0x20,0xc0 # movl %cr0, %eax ; Get control register 0 .byte 0x66 .byte 0x83,0xe0,0xfe # and eax, 0fffffffeh ; Clear PE bit (bit #0) .byte 0xf,0x22,0xc0 # mov cr0, eax ; Activate real mode The 2nd lret is reached (just before _AsmTransferControl_al_0001), but then the CPU goes off in the woods. For a while it seems to be spinning who knows where, and in 15-20 seconds or so the guest reboots. Does gas support mode switches in one file? I found examples on the net (for nasm I think) where people were thunking to real mode and back to protected mode in a single assembly file, and they could use native mnemonics for each part. (They just switched the assembler's mode in sync with execution modes.) Thanks Laszlo Thanks, Laszlo ------------------------------------------------------------------------------ Sponsored by Intel(R) XDK Develop, test and display web and hybrid apps with a single code base. Download it for free now! http://pubads.g.doubleclick.net/gampad/clk?id=111408631&iu=/4140/ostg.clktrk _______________________________________________ edk2-devel mailing list edk2-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/edk2-devel