On Wed, Oct 29, 2014 at 05:48:10AM +0000, Vyacheslav Barinov wrote: > James Greenhalgh <james.greenhalgh@xxxxxxx> writes: > > On Tue, Oct 28, 2014 at 05:29:15AM +0000, Slava Barinov wrote: > >> I work now with ARM64 CPUs and wanted to check AArch32 mode, I can see > >> several mentions in GCC source code but can't find flag which switches on > >> AArch32 code generation. > >> > >> Is it possible to make current GCC generate it? > > > > AArch32 is the 32-bit execution state in the ARMv8 architecture. It is > > closely related to the ARMv7 architecture, which in GCC is implemented as > > the "arm" target. Code generation for the AArch64 execution state of the > > ARMv8 architecture is implemented as the "aarch64" target. > > > > GCC has a model whereby the compiler can be built for only one target at > > any time, so there is no flag which will generate AArch32 code from an > > AArch64 compiler. You will need a compiler built to target "arm". > > > > For your use case that will mean installing two cross-compilers, one for > > (for example) arm-none-linux-gnueabi, and one for aarch64-none-linux-gnu. > > That was the first thing I tried and it works partially. > But my initial idea was to use armv8 hardware extensions like accelerated > crypto engine. > > Will setting CPU model to armv8 in arm-none-linux-gnueabi toolchain make it > possible to use all its features in 32bit code? Initial support in the ARM port for ARMv8-A was added in GCC 4.8. Support for the ARMv8-A Crypto extension, and for the CRC instructions, was added to the ARM port in GCC 4.9 [1]. To enable support for the CRC intrinsics you should use: -march=armv8-a+crc To enable support for the Crypto intrinsics you should use: -mfpu=crypto-neon-fp-armv8 You can look at: https://gcc.gnu.org/onlinedocs/gcc/ARM-Options.html for more details on the available options for the ARM target. Thanks, James --- [1]: GCC 4.9 Release Series Changes, New Features, and Fixes https://gcc.gnu.org/gcc-4.9/changes.html
