Re: [Qemu-devel] [PATCH] Add configure clock_gettime() monotonic time test

[Paolo Bonzini <pbonzini@redhat.com>]

Il 03/04/2013 00:52, Peter Maydell ha scritto:
> On 2 April 2013 17:45, Paolo Bonzini <pbonzini@redhat.com> wrote:
>> Il 02/04/2013 17:42, Brad Smith ha scritto:
>>> Replace the hardcoded list of OS's utilizing clock_gettime() for monotonic
>>> time with a configure test. This is to fix the use of monotonic time on
>>> OpenBSD but allows for other POSIX compliant OS's such as NetBSD to also
>>> utilize clock_gettime().
>>
>> I thought the list of OSes was supposed to filter out those that somehow
>> had a broken CLOCK_MONOTONIC.
> 
> Judging from wading through git history, it's mostly just
> historic accretion from an initial #ifdef __linux__ which was
> put in by Fabrice way back when configure was barely doing
> compile-this-code checks at all.
> 
> Google does suggest that some OSes do provide a CLOCK_MONOTONIC
> but clock_gettime(CLOCK_MONOTONIC) always fails, eg Centos 3.

It would already fail, and no one reported it.

CentOS 3 has a 2.4 kernel.  I doubt anyone is using it with a recent QEMU.

Paolo

>> Otherwise, you might as well use "#ifdef CLOCK_MONOTONIC" and skip the
>> configure test completely.
> 
> Tempting.
> 
> -- PMM
> 
>