svn commit: r194040 - stable/7/lib/libc/gen

Jilles Tjoelker jilles at
Fri Jun 12 13:34:47 UTC 2009

On Fri, Jun 12, 2009 at 08:51:32AM -0400, John Baldwin wrote:
> On Friday 12 June 2009 6:13:08 am Dmitry Morozovsky wrote:
> > On Thu, 11 Jun 2009, John Baldwin wrote:
> > 
> > JB> Author: jhb
> > JB> Date: Thu Jun 11 21:37:23 2009
> > JB> New Revision: 194040
> > JB> URL:
> > JB> 
> > JB> Log:
> > JB>   If the running kernel has support for shm_open() and shm_unlink() as
> > JB>   system calls (i.e. 8.0+), then invoke the system calls instead of using
> > JB>   open/fcntl/unlink.  This is a direct commit instead of an MFC since libc
> > JB>   in 8.0 always uses the system calls directly.
> > 
> > So it could help running RELENG_7 jails under 8 host? 

> In that case it probably doesn't matter either way.  The goal is that if you
> have an 8.x binary and a 7.x binary that are both using shm_open() with a
> path to open a SHM region for IPC, they will both access the same object.

> If you have all 8.x binaries or all < 8.x binaries in the group that shares
> access to a named SHM region then that case would work regardless.

where "< 8.x binaries" refers to those using 7.x's
Normally, a 7.x binary running on 8.x will link to 8.x's and
therefore use the new SHM objects even without this change.

The change will likely help people that link statically to libc (boo!)
or do weird things with the 7.x file.

Jilles Tjoelker

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