On 31 December 2015 at 13:57, Ard Biesheuvel <ard.biesheu...@linaro.org> wrote: > This is a followup to the patch 'BaseTools AARCH64: add -mstrict-align to > all AARCH64 GCC flavors' that I sent out on the 23rd. As it turns out, using > strict alignment results in a code size increase which breaks the build for > the DEBUG shell using the tiny code model we use for GCC49 and up. > > I have reproduced some patches here that I have already sent out separately > (#5) or as part of another series (#1, #2) but I included them again since > they need to be merged in order to prevent breaking bisect due to build > errors. > > Changes since v1: > - Dropped the patches that rely on function alignment to sort the input > objects > in a way that results in the tiny model objects to end up in close proximity > of each other. This is unmaintainable hack, and since the issue it solves > only > affects the DEBUG builds, we can simply switch to the small code model for > everything and not care about the code size increase. > - Added some R-b's from Liming and Leif. > > Patches #1 and #2 set the CLANG35 target to the GNU flavor of the respective > architectures, and adds the target to the preprocessor invocations as well. > > Patch #3 changes the default code model for all DEBUG_GCC49 generated code > to the small model, and updates the minimal alignment accordingly. This allows > us to get rid of module or module type specific overrides, which are difficult > to maintain. This results in a slight size increase, but code size is not such > a big concern for DEBUG builds anyway. Below are the compressed/uncompressed > sizes of ArmVirtQemu.dsc built with the various code models (built without > support for secure boot). Note that this includes the -mstrict-align switch > added in patch #5. > > | tiny | small | large | small / best | > ---------+----------------+----------------+----------------+---------------+ > DEBUG | does not build | 1376k/7958k | 1297k/7360k | +6%/+8% | > ---------+----------------+----------------+----------------+---------------+ > RELEASE | 772k/3897k | 904k/4636k | 791k/4321k | +17%/+19% | > ---------+----------------+----------------+----------------+---------------+ > > Patch #4 removes the build options for AARCH64 from ShellPkg. They need to be > overridden anyway or they will only affect the core Shell binary and not all > of > the Shell component libraries that are merged with the core binary at build > time. > Also, we only need this override for GCC49, since GCC 48 and earlier use the > large code model, and CLANG35 uses the small code model. > > Patch #5 moves the -mstrict-align compiler option to the common AARCH64/GCC > CFLAGS definition so that it applies to all GCC versions in addition to > CLANG35. > This addresses an issue spotted by the Ubuntu/Debian folks (and which they > kindly never reported upstream, afaict) here: > https://bugs.launchpad.net/ubuntu/+source/edk2/+bug/1489560 > > Ard Biesheuvel (5): > BaseTools CLANG35: use GNU target triplets explicitly > BaseTools CLANG35: use -target in PP flags as well > BaseTools AARCH64: move DEBUG GCC49 to the small code model > ShellPkg AARCH64: remove DEBUG BuildOptions override > BaseTools AARCH64: add -mstrict-align to all AARCH64 GCC flavors >
Hello all, I have committed patches #1 and #2 of this series as SVN r19583 and r19584. For the remaining ones, I will follow up with an alternate approach to implement the strict alignment, using build rules. -- Ard. _______________________________________________ edk2-devel mailing list edk2-devel@lists.01.org https://lists.01.org/mailman/listinfo/edk2-devel
