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Re: [RFC][PATCH] ARM: vDSO support
- From: "Joseph S. Myers" <joseph at codesourcery dot com>
- To: Nathan Lynch <nathan_lynch at mentor dot com>
- Cc: <libc-alpha at sourceware dot org>
- Date: Wed, 26 Feb 2014 02:01:03 +0000
- Subject: Re: [RFC][PATCH] ARM: vDSO support
- Authentication-results: sourceware.org; auth=none
- References: <1393373216-30253-1-git-send-email-nathan_lynch at mentor dot com>
On Tue, 25 Feb 2014, Nathan Lynch wrote:
> Future versions (beginning with 3.15 or 3.16) of Linux on 32-bit ARM
> are expected to provide fast user-space implementations of the
> following system calls:
>
> - gettimeofday
> - clock_gettime
> - clock_getres
>
> This patch adds support for the ARM vDSO to glibc. The changes are
> mostly copied from the aarch64 code, with necessary adjustments to
> _libc_vdso_platform_setup and INTERNAL_VSYSCALL_NCS (which has
> __thumb2__ and non-__thumb2__ versions).
It would be best to add this only once the changes are actually in the
kernel, given that it depends on a kernel/userspace ABI that involves a
version number.
> Tested on OMAP5 (Cortex-A15) with the relevant kernel patch, the latest
> posted version of which may be found here:
Testing with a kernel without the feature is also important.
> 2014-02-25 Nathan Lynch <nathan_lynch@mentor.com>
Mentor's FSF copyright assignment only applies to people with an
@codesourcery.com address, so it is advisable to use such an address when
posting patches to GNU projects.
> +int
> +__gettimeofday (tv, tz)
> + struct timeval *tv;
> + struct timezone *tz;
New old-style function definitions should be avoided (I hope at some point
we can eliminate the existing ones and start using -Wold-style-definition
by default).
--
Joseph S. Myers
joseph@codesourcery.com