Hi Laszlo "I'm asking because I'm now reaching the assembly code in "MdeModulePkg/Universal/Acpi/BootScriptExecutorDxe/X64/S3Asm.S" that would jump to the (real mode) OSPM waking vector, and it reboots the machine. I think that maybe the wrong routine is invoked, due to confusion around PcdDxeIplSwitchToLongMode."
OSPM waking vector mode is NOT related to PcdDxeIplSwitchToLongMode. OSPM waking vector is defined by ACPI spec, and set by OS, and referred by BIOS. PcdDxeIplSwitchToLongMode is only UDK internal implementation. It is not used by any OSPM. Thank you Yao Jiewen -----Original Message----- From: Laszlo Ersek [mailto:ler...@redhat.com] Sent: Wednesday, December 04, 2013 5:56 AM To: edk2-devel@lists.sourceforge.net Subject: [edk2] please clarify "PcdDxeIplSwitchToLongMode" Hi, it's as if different parts of the code thought differently about PcdDxeIplSwitchToLongMode. Interpretation #1: - PcdDxeIplSwitchToLongMode means that we have to *switch* from 32-bit PEI to 64-bit DXE. Emphasis on "switch", that is, "PEI and DXE have different bitness". Interpretation #2: - PcdDxeIplSwitchToLongMode means that DXE is 64-bit, independently of PEI bitness. PcdDxeIplSwitchToLongMode PEI DXE Interp#1 Interp#2 result 32 32 0 0 OK 32 64 1 1 OK 64 64 0 1 oops I checked the documentation in MdeModulePkg/MdeModulePkg.dec, and I have no clue which interpretation it follows. The picture is further complicated by "PcdDxeIplBuildPageTables" (added in SVN r12016. It seems to allow one to say (by setting it to FALSE), "64-bit PEI, 64-bit DXE, but please don't rebuild page tables". Now, in OVMF, the 32/32 platform DSC file sets PcdDxeIplSwitchToLongMode to FALSE. No difference between interp#1 and interp#2. The 32/64 DSC file sets it to TRUE. Detto. The 64/64 DSC file it to FALSE again, clearly following interp#1 -- "no switching needed". Maybe, we should set this PCD to TRUE (ie. follow Interp#2), and turn off rebuilding the page tables by setting the newer PcdDxeIplBuildPageTables to FALSE. I have no clue. (We don't use this second PCD in OVMF, only EmulatorPkg and Nt32Pkg do -- they both set it to FALSE.) If OVMF interprets PcdDxeIplSwitchToLongMode differently (==interp#1) from some other parts of the code (interp#2), well that has not been causing problems until now, apparently. But now I'm looking at the S3 suspend/resume code, and it is full of comments that apparently *equate* PcdDxeIplSwitchToLongMode==FALSE with DXE is 32-bit Which corresponds to Interp#2. I'm asking because I'm now reaching the assembly code in "MdeModulePkg/Universal/Acpi/BootScriptExecutorDxe/X64/S3Asm.S" that would jump to the (real mode) OSPM waking vector, and it reboots the machine. I think that maybe the wrong routine is invoked, due to confusion around PcdDxeIplSwitchToLongMode. (The reboot happens when LRET pops RIP and CS from the stack. Apparently the idea behind this exercise is to stay/continue in the same ASM file, but change the CS. It doesn't work.) 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 ------------------------------------------------------------------------------ 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
