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In GCC 4.7, a feature was added to the ARM backend that allows unaligned loads and stores to be emitted. Since it is enabled by default on ARMv6 and later CPUs, and since such code is not suitable in our case (i.e., bare metal code), we must disable it by passing the -mno-unaligned-access option if we are using GCC 4.7 or later. However, this particular feature and its enabling by default have been backported to version 4.6 by Linaro. Since the Linaro toolchains are widely used for ARM development, and also shipped by distros such as Ubuntu, we should disable the feature on version 4.6 as well. Unfortunately, since the upstream version does not support the feature, it also does not understand the -mno-unaligned-access option. Since GCC sets the builtin #define __ARM_FEATURE_UNALIGNED to 1 when -munaligned-access is in effect, we can force the build to fail in this case by passing -D__ARM_FEATURE_UNALIGNED=0 on the GCC command line. This will produce the following error message: <command-line>:0:0: error: "__ARM_FEATURE_UNALIGNED" redefined [-Werror] <built-in>:0:0: note: this is the location of the previous definition and terminate the build. This patch may cause some existing builds to fail, but they will be builds that were previously at risk of unexpected runtime exceptions. Those builds can also easily be switched to the GCC47 profile instead, generating safe binaries. Contributed-under: TianoCore Contribution Agreement 1.0 Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> Reviewed-by: Leif Lindholm <leif.lindholm@linaro.org> git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@18228 6f19259b-4bc3-4df7-8a09-765794883524
This directory contains the template files for the next generation of the EDK II Build infrastructure. These files will be copied into the WORKSPACE's Conf directory if and only if the target files do not exist. These files may be updated frequently. The XMLSchema directory contains the EDK II Packaging XML definitions. The schema may change in the future. It differs somewhat from the early versions of the XML Schema.