Messages in this thread | | | Date | Mon, 20 Jan 2014 12:44:19 -0500 (EST) | From | Nicolas Pitre <> | Subject | Re: [PATCH v2 0/5] arm64: advertise availability of CRC and crypto instructions |
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On Mon, 20 Jan 2014, Catalin Marinas wrote:
> On Mon, Dec 23, 2013 at 02:06:27PM +0000, Ard Biesheuvel wrote: > > 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.
How could older glibc possibly care about future extensions?
Nicolas
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