Re: port-amd64/47967: DTrace does not work while running under QEMU

[David Laight <david%l8s.co.uk@localhost>]

The following reply was made to PR port-amd64/47967; it has been noted by GNATS.

From: David Laight <david%l8s.co.uk@localhost>
To: gnats-bugs%NetBSD.org@localhost
Cc: port-amd64-maintainer%netbsd.org@localhost, 
gnats-admin%netbsd.org@localhost,
        netbsd-bugs%netbsd.org@localhost
Subject: Re: port-amd64/47967: DTrace does not work while running under QEMU
Date: Wed, 26 Jun 2013 22:30:00 +0100

 On Wed, Jun 26, 2013 at 05:35:00PM +0000, riz%NetBSD.org@localhost wrote:
 > >Synopsis:       tsc_freq is 0 when running under QEMU so DTrace crashes at 
 > >load
 ...
 >  static void
 > +cpu_probe_qemu(struct cpu_info *ci)
 > +{
 > +       if (memcmp("QEMU Virtual CPU", cpu_brand_string, 16) != 0)
 > +               return;
 > +
 > +       /* if QEMU does not implement MSR_TSC, disable the TSC */
 > +       ci->ci_feat_val[0] &= ~CPUID_MSR;
 > +       cpu_feature[0] &= ~CPUID_MSR;
 > +}
 
 Surely it would be much better to probe for the symptom, rather
 than a random string.
 
        David
 
 -- 
 David Laight: david%l8s.co.uk@localhost