Intel Advanced Matrix Extensions (AMX) are a new set registers and ISA. They are conceptually similar to the earlier AVX and SSE ISA. But, the registers as a whole are *really* big: ~8k verus 2k for AVX-512. Those amply-sized registers present some potential problems with task_struct and signal stack bloat. To fix those issues, most of the new AMX state is dynamically allocated with the help of a new CPU feature. This new selftest exercises the new dynamic allocation ABI and also ensures that AMX state is properly context-switched. Processors that support AMX (Sapphire Rapids) are not publicly available. The kernel support needed to run these tests is not upstream. This selftest was developed against this tree: https://git.kernel.org/pub/scm/linux/kernel/git/tglx/devel.git/log/?h=x86/fpu These tests were primarily written by Chang Bae. He's busy working on the real kernel support, so I stole these and cleaned them up a bit. Chang S. Bae (2): selftest/x86/amx: Test cases for the AMX state management selftest/x86/amx: Add context switch test tools/testing/selftests/x86/Makefile | 2 +- tools/testing/selftests/x86/amx.c | 851 +++++++++++++++++++++++++++ 2 files changed, 852 insertions(+), 1 deletion(-) Signed-off-by: Chang S. Bae <chang.seok.bae@xxxxxxxxx> Signed-off-by: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx> Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx> Cc: x86@xxxxxxxxxx Cc: linux-kernel@xxxxxxxxxxxxxxx Cc: linux-kselftest@xxxxxxxxxxxxxxx
