[RFC] SysV SHM on 64-bit platforms

David Schultz das at FreeBSD.ORG
Sat Jan 19 04:13:44 PST 2008


On Fri, Jan 18, 2008, Jung-uk Kim wrote:
> Because fixing this PR breaks ABI, I had to make compat shims.  But 
> the question is which branch to break?  Since we are very close to 
> 7.0-RELEASE, the question became more complicated.  A lot of people 
> are asking me to fix this PR because it is much needed fix for large 
> database installations, so I have to make a quick decision. :-(

It's far too late to fix it for 7.0. RC1 is out, the packages have
already been built, and this could potentially break things. In
particular, you have no way of guaranteeing that an "old" shared
library that uses semctl(2) linked with a "new" binary will work
properly, or vise versa.

For 8-CURRENT, I'd say go ahead and fix it and add the syscall
compat goop. Then I guess backport it to 7-STABLE after a while if
nothing important breaks and nobody has any objections to that plan.

It would also be cool if struct ipcperm got fixed at the same time
so we only have to do this once. I think that only entails adding
compat crud to semctl and maybe one or two other syscalls. Those
changes aren't urgent enough to make it worthwhile to backport to
7.X IMO, though.

Two questions/comments about the patches:
- Why the #if !defined(__i386__)? There are better ways to test
  whether you're compiling for a 32-bit architecture, if that's
  what you meant.
- The 8.X version needs to take the p_osrel for the equivalent
  change in 7.X into account.


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