[PATCH v2 0/5] arm64: advertise availability of CRC and crypto instructions
From: Ard Biesheuvel <hidden>
Date: 2014-01-21 08:55:53
@Russell, May we have your comments/opinion please on this alternative approach? Regards, Ard. On 20 January 2014 18:38, Catalin Marinas [off-list ref] wrote:
On Mon, Dec 23, 2013 at 02:06:27PM +0000, Ard Biesheuvel wrote:quoted
This series is a followup to the patch that was recently merged by Catalin that allocates hwcaps bits for CRC and Crypto Extensions instructions so userland can discover whether the current CPU has any of those capabilities. Patch #1 enables ARM support for the ELF_HWCAP2/AT_HWCAP2 ELF auxv entry that was recently added to the kernel and glibc (2.18). It extends the feature bit space to 64 bits (on 32-bit architectures) Patch #2 adds generic support for ELF_HWCAP2/AT_HWCAP2 to the 32-bit ELF compat mode for 64-bit architectures. Patch #3 adds support for ELF_HWCAP2/AT_HWCAP2 to arm64's 32-bit ELF compat mode Patch #4 allocates the HWCAP2 bits in the arch/arm tree. This is necessary because 32-bit ARM binaries can execute both under ARM and under arm64 kernels, so there should be agreement about the meaning of feature bits, even if the ARM kernel has no support yet for ARMv8 32-bit only hardware (such as ARMv8-R).It looks a bit strange to start filling HWCAP2 before HWCAP is full but I guess we want to preserve some future extensions in HWCAP for older glibc. -- Catalin