Messages in this thread | | | Date | Wed, 1 Mar 2006 07:56:38 +0000 (GMT) | From | Hugh Dickins <> | Subject | Re: why VM_SHM has been removed from mm.h? |
| |
On Tue, 28 Feb 2006, Kamran Karimi wrote: > > VM_SHM is used by DIPC to quickly recognise when we are dealing with a System > V IPC segment. It has been "removed" from recent kernels (set to 0).
Curious: VM_SHM wasn't set on a System V IPC shm vma in any 2.4 or 2.6 kernel that I know of; but was set on the vmas of a random collection of drivers. Perhaps you've been using your own patch to set it on SysV IPC shm vmas, and clear it from drivers' vmas?
(We'll remove VM_SHM entirely once I've trawled through those drivers.)
> Is there an easy way to find out if a segment is a Sys V shm?
Nothing easy and reliable springs immediately to mind - from a VM point of view, they're treated much the same as tmpfs files; but there probably is some hacky way if we think about it long enough.
> if not, I suggest we re-activate it.
It seems that either you've been doing the wrong thing up to now, and never noticed it; or that you've been using your own flag in your own patch, and can continue to do so. No need for vanilla kernel to reinstate VM_SHM.
Are you sure you need to recognize them?
Hugh - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
| |