svn commit: r216161 - in head/sys: amd64/amd64 i386/i386
jkim at FreeBSD.org
Fri Dec 3 23:02:48 UTC 2010
On Friday 03 December 2010 05:43 pm, Jung-uk Kim wrote:
> On Friday 03 December 2010 05:08 pm, John Baldwin wrote:
> > On Friday, December 03, 2010 4:54:10 pm Jung-uk Kim wrote:
> > > Author: jkim
> > > Date: Fri Dec 3 21:54:10 2010
> > > New Revision: 216161
> > > URL: http://svn.freebsd.org/changeset/base/216161
> > >
> > > Log:
> > > Explicitly initialize TSC frequency. To calibrate TSC
> > > frequency, we use DELAY(9) and it may use TSC in turn if TSC
> > > frequency is non-zero.
> > We zero the BSS, so these were already zero. This just makes the
> > actual kernel file on disk larger by wasting space in .data
> > instead of .bss.
> Please note that I didn't touch other variables, e.g.,
> tsc_is_broken, because I knew that. However, I just wanted to do
> that *explicitly*. Anyway, it is reverted now and SVN will remember
> what I wanted to do. ;-)
> BTW, if my memory serves, GCC (and all modern C compilers) put(s)
> zero-initialized variables back in .bss.
I just tried it. GCC generates identical binaries as I thought.
However, Clang doesn't do the optimization. :-/
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