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Re: [PATCH v2] tunables, aarch64: New tunable to override cpu
- From: Carlos O'Donell <carlos at redhat dot com>
- To: Siddhesh Poyarekar <siddhesh at sourceware dot org>, libc-alpha at sourceware dot org
- Date: Thu, 29 Jun 2017 08:17:06 -0400
- Subject: Re: [PATCH v2] tunables, aarch64: New tunable to override cpu
- Authentication-results: sourceware.org; auth=none
- References: <1498729954-15927-1-git-send-email-siddhesh@sourceware.org>
On 06/29/2017 05:52 AM, Siddhesh Poyarekar wrote:
> Add a new tunable (glibc.tune.cpu) to override CPU identification on
> aarch64. This is useful in two cases: one where it is desirable to
> pretend to be another CPU for purposes of testing or because routines
> written for that CPU are beneficial for specific workloads and second
> where the underlying kernel does not support emulation of MRS to get
> the MIDR of the CPU.
>
> * elf/dl-tunables.h (tunable_is_name): Move from...
> * elf/dl-tunables.c (is_name): ... here.
> (parse_tunables, __tunables_init): Adjust.
> * manual/tunables.texi: Document glibc.tune.cpu.
> * sysdeps/aarch64/dl-tunables.list: New file.
> * sysdeps/unix/sysv/linux/aarch64/cpu-features.c (struct
> cpu_list): New type.
> (cpu_list): New list of CPU names and their MIDR.
> (get_midr_from_mcpu): New function.
> (init_cpu_features): Override MIDR if necessary.
Looks good to me.
I assume it defaults to SXID_ERASE.
--
Cheers,
Carlos.