From 6064c1e48b622f53538f4df9bdd402c607a87d51 Mon Sep 17 00:00:00 2001 From: Konstantin Aladyshev <aladyshev22@gmail.com> Date: Sat, 10 Jul 2021 00:04:40 +0300 Subject: Move lessons to separate folder Signed-off-by: Konstantin Aladyshev <aladyshev22@gmail.com> --- Lesson_23/README.md | 225 ---------------------------------------------------- 1 file changed, 225 deletions(-) delete mode 100644 Lesson_23/README.md (limited to 'Lesson_23') diff --git a/Lesson_23/README.md b/Lesson_23/README.md deleted file mode 100644 index bae429d..0000000 --- a/Lesson_23/README.md +++ /dev/null @@ -1,225 +0,0 @@ -Now let's explore `PatchableInModule` PCD. - -Add PCD to DEC file UefiLessonsPkg/UefiLessonsPkg.dec: -``` -[PcdsPatchableInModule] - gUefiLessonsPkgTokenSpaceGuid.PcdMyPatchableVar32|0x31313131|UINT32|0x00000004 -``` -Populate it to INF UefiLessonsPkg/PCDLesson/PCDLesson.inf: -``` -[PatchPcd] - gUefiLessonsPkgTokenSpaceGuid.PcdMyPatchableVar32 -``` - -To get a value of PCD in a *.c file either `PatchPcdGet` or generic `PcdGet` should be used. - -Let's test both methods: -``` -Print(L"PcdMyPatchableVar32=%d\n", PatchPcdGet32(PcdMyPatchableVar32)); -Print(L"PcdMyPatchableVar32=%d\n", PcdGet32(PcdMyPatchableVar32)); -``` - -Now build and look to AutoGen files: - -Build/UefiLessonsPkg/RELEASE_GCC5/X64/UefiLessonsPkg/PCDLesson/PCDLesson/DEBUG/AutoGen.h -``` -#define _PCD_TOKEN_PcdMyPatchableVar32 0U -#define _PCD_PATCHABLE_VALUE_PcdMyPatchableVar32 ((UINT32)0x31313131U) -extern volatile UINT32 _gPcd_BinaryPatch_PcdMyPatchableVar32; -#define _PCD_GET_MODE_32_PcdMyPatchableVar32 _gPcd_BinaryPatch_PcdMyPatchableVar32 -#define _PCD_PATCHABLE_PcdMyPatchableVar32_SIZE 4 -#define _PCD_GET_MODE_SIZE_PcdMyPatchableVar32 _gPcd_BinaryPatch_Size_PcdMyPatchableVar32 -extern UINTN _gPcd_BinaryPatch_Size_PcdMyPatchableVar32; -#define _PCD_SET_MODE_32_PcdMyPatchableVar32(Value) (_gPcd_BinaryPatch_PcdMyPatchableVar32 = (Value)) -#define _PCD_SET_MODE_32_S_PcdMyPatchableVar32(Value) ((_gPcd_BinaryPatch_PcdMyPatchableVar32 = (Value)), RETURN_SUCCESS) -``` -Build/UefiLessonsPkg/RELEASE_GCC5/X64/UefiLessonsPkg/PCDLesson/PCDLesson/DEBUG/AutoGen.c -``` -volatile UINT32 _gPcd_BinaryPatch_PcdMyPatchableVar32 = _PCD_PATCHABLE_VALUE_PcdMyPatchableVar32; -GLOBAL_REMOVE_IF_UNREFERENCED UINTN _gPcd_BinaryPatch_Size_PcdMyPatchableVar32 = 4; -``` - -So in this case our call to `PcdGet32(PcdMyPatchableVar32)` would be expanded to: -``` -PcdGet32(PcdMyPatchableVar32) --> _PCD_GET_MODE_32_PcdMyPatchableVar32 --> _gPcd_BinaryPatch_PcdMyPatchableVar32 -``` -This variable would be assigned in `AutoGen.c`: -``` -volatile UINT32 _gPcd_BinaryPatch_PcdMyPatchableVar32 = ((UINT32)0x31313131U); -``` -So the main difference from the FixedAtBuild and FeatureFlag PCDs is that variable defined as `volatile` and set functions aren't blocked. - -Let's try to set our PCD then. As with get, there are two possibilities. You can use either `PatchPcdSet<Type>` or generic `PcdSet<Type>S`. - -Keep in mind that `PcdSet32S` unravels to a macro returning a value. -https://github.com/tianocore/edk2/blob/master/MdePkg/Include/Library/PcdLib.h: -``` -#define PcdSet32S(TokenName, Value) _PCD_SET_MODE_32_S_##TokenName ((Value)) -``` -Therefore: -``` -PcdSet32S(PcdMyPatchableVar32, 44) --> _PCD_SET_MODE_32_S_PcdMyPatchableVar32 ((Value)) --> ((_gPcd_BinaryPatch_PcdMyPatchableVar32 = (Value)), RETURN_SUCCESS) -``` - -So if you don't want such error: -``` -/home/kostr/tiano/edk2/Build/UefiLessonsPkg/RELEASE_GCC5/X64/UefiLessonsPkg/PCDLesson/PCDLesson/DEBUG/AutoGen.h:108:106: error: right-hand operand of comma expression has no effect [-Werror=unused-value] - 108 | #define _PCD_SET_MODE_32_S_PcdMyPatchableVar32(Value) ((_gPcd_BinaryPatch_PcdMyPatchableVar32 = (Value)), RETURN_SUCCESS) - | ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~. -``` -You should use something like this: -``` -RETURN_STATUS PcdStatus = PcdSet32S(PcdMyPatchableVar32, 44); -Print(L"PcdStatus=%r\n", PcdStatus); -``` - -Alternatively you can use `PatchPcdSet32` which don't require such thing as it is defined as follows: -``` -#define PatchPcdSet32(TokenName, Value) (_gPcd_BinaryPatch_##TokenName = (Value)) -``` - -Test both set methods in app code: -``` -Print(L"PcdMyPatchableVar32=0x%x\n", PcdGet32(PcdMyPatchableVar32)); -RETURN_STATUS PcdStatus = PcdSet32S(PcdMyPatchableVar32, 44); -Print(L"PcdStatus=%r\n", PcdStatus); -Print(L"PcdMyPatchableVar32=%d\n", PcdGet32(PcdMyPatchableVar32)); -PatchPcdSet32(PcdMyPatchableVar32, 45); -Print(L"PcdMyPatchableVar32=%d\n", PatchPcdGet32(PcdMyPatchableVar32)); -``` - - -Now if you execute our app under OVMF prints for patchable PCDs would output: -``` -PcdMyPatchableVar32=0x31313131 -PcdStatus=Success -PcdMyPatchableVar32=44 -PcdMyPatchableVar32=45 -``` - -_________________________________ - -In case you've wondered why I've assigned a hex value for PCD default value or why this PCD type is named `PatchableInModule` this section is for you. - -This PCD type is named like that because the value of this PCD can be changed in a binary PE/COFF image (*.efi file). To do this two utilities are used: -- `GenPatchPcdTable` - this tool is used to get the patchable PCD offset for the EFI image by parsing the map file -- `PatchPcdValue` - this tool is used to actually patch PCD value - -You can download rtf manuals for these utilities from edk2 repo: --https://github.com/tianocore/edk2/blob/master/BaseTools/UserManuals/GenPatchPcdTable_Utility_Man_Page.rtf --https://github.com/tianocore/edk2/blob/master/BaseTools/UserManuals/PatchPcdValue_Utility_Man_Page.rtf - -Let's start with `GenPatchPcdTable`. First check out help for this tool: -``` -$ ./BaseTools/BinWrappers/PosixLike/GenPatchPcdTable -h -Usage: GenPatchPcdTable.py -m <MapFile> -e <EfiFile> -o <OutFile> - -Copyright (c) 2008 - 2018, Intel Corporation. All rights reserved. - -Options: - --version show program's version number and exit - -h, --help show this help message and exit - -m MAPFILE, --mapfile=MAPFILE - Absolute path of module map file. - -e EFIFILE, --efifile=EFIFILE - Absolute path of EFI binary file. - -o OUTFILE, --outputfile=OUTFILE - Absolute path of output file to store the got - patchable PCD table. -``` -Now let's create a `PatchPcdTable` for our app: - -For the *.efi file we can use one of: -``` -Build/UefiLessonsPkg/RELEASE_GCC5/X64/PCDLesson.efi -Build/UefiLessonsPkg/RELEASE_GCC5/X64/UefiLessonsPkg/PCDLesson/PCDLesson/OUTPUT/PCDLesson.efi -Build/UefiLessonsPkg/RELEASE_GCC5/X64/UefiLessonsPkg/PCDLesson/PCDLesson/DEBUG/PCDLesson.efi -``` -For the *.map file we can use one of: -``` -Build/UefiLessonsPkg/RELEASE_GCC5/X64/UefiLessonsPkg/PCDLesson/PCDLesson/DEBUG/PCDLesson.map -Build/UefiLessonsPkg/RELEASE_GCC5/X64/UefiLessonsPkg/PCDLesson/PCDLesson/OUTPUT/PCDLesson.map -``` -In case you wonder how our PCD can be found in a map file, execute: -``` -$ grep MyPatchableVar32 Build/UefiLessonsPkg/RELEASE_GCC5/X64/UefiLessonsPkg/PCDLesson/PCDLesson/DEBUG/PCDLesson.map -A2 - .data._gPcd_BinaryPatch_PcdMyPatchableVar32 - 0x0000000000001920 0x4 /tmp/PCDLesson.dll.m6t8YL.ltrans0.ltrans.o - *fill* 0x0000000000001924 0xc -``` -So as you can see the default value for our PCD is placed under 0x1920 offset. - -Now let's execute `GenPatchPcdTable` and create a file `PCDLessonPatchPcdTable` in app Build DEBUG folder: -``` -./BaseTools/BinWrappers/PosixLike/GenPatchPcdTable \ - -m Build/UefiLessonsPkg/RELEASE_GCC5/X64/UefiLessonsPkg/PCDLesson/PCDLesson/DEBUG/PCDLesson.map \ - -e Build/UefiLessonsPkg/RELEASE_GCC5/X64/UefiLessonsPkg/PCDLesson/PCDLesson/DEBUG/PCDLesson.efi \ - -o Build/UefiLessonsPkg/RELEASE_GCC5/X64/UefiLessonsPkg/PCDLesson/PCDLesson/DEBUG/PCDLessonPatchPcdTable -``` - -Checkout the created `PCDLessonPatchPcdTable` file. -``` -$ cat Build/UefiLessonsPkg/RELEASE_GCC5/X64/UefiLessonsPkg/PCDLesson/PCDLesson/DEBUG/PCDLessonPatchPcdTable -PCD Name Offset Section Name -PcdMyPatchableVar32 0x1920 .data -``` -As you can see it has the same offset that we've seen in a map file. - -Now let's get a final look at our default PCD value in an *.elf file: -``` -hexdump -s 0x1920 Build/UefiLessonsPkg/RELEASE_GCC5/X64/UefiLessonsPkg/PCDLesson/PCDLesson/DEBUG/PCDLesson.efi -n 4 -0001920 3131 3131 -0001924 -``` - -Checkout help for the `PatchPcdValue` tool: -``` -$ ./BaseTools/BinWrappers/PosixLike/PatchPcdValue -h -Usage: PatchPcdValue.py -f Offset -u Value -t Type [-s MaxSize] <input_file> - -Copyright (c) 2010 - 2018, Intel Corporation. All rights reserved. - -Options: - -f PCDOFFSET, --offset=PCDOFFSET - Start offset to the image is used to store PCD value. - -u PCDVALUE, --value=PCDVALUE - PCD value will be updated into the image. - -t PCDTYPENAME, --type=PCDTYPENAME - The name of PCD data type may be one of VOID*,BOOLEAN, - UINT8, UINT16, UINT32, UINT64. - -s PCDMAXSIZE, --maxsize=PCDMAXSIZE - Max size of data buffer is taken by PCD value.It must - be set when PCD type is VOID*. - -v, --verbose Run verbosely - -d LOGLEVEL, --debug=LOGLEVEL - Run with debug information - -q, --quiet Run quietly - -? show this help message and exit - --version show program's version number and exit - -h, --help show this help message and exit -``` - -Now use it to patch our PCD in an *.elf file: -``` -./BaseTools/BinWrappers/PosixLike/PatchPcdValue \ - --offset=0x1920 \ - --value=0xDEADDEAD \ - --type=UINT32 \ - Build/UefiLessonsPkg/RELEASE_GCC5/X64/UefiLessonsPkg/PCDLesson/PCDLesson/DEBUG/PCDLesson.efi -``` -Look at hexdump again: -``` -$ hexdump -s 0x1920 Build/UefiLessonsPkg/RELEASE_GCC5/X64/UefiLessonsPkg/PCDLesson/PCDLesson/DEBUG/PCDLesson.efi -n 4 -0001920 dead dead -0001924 -``` -We've successfully changed our PCD in a binary! - -Now if you execute our app under OVMF prints for patchable PCDs would output: -``` -PcdMyPatchableVar32=0xDEADDEAD -PcdStatus=Success -PcdMyPatchableVar32=44 -PcdMyPatchableVar32=45 -``` - -- cgit v1.2.3-18-g5258