On Tue, 22 May 2007 15:51:35 -0700 Stephane Eranian <[EMAIL PROTECTED]> wrote:
> Andrew, > > On Tue, May 22, 2007 at 09:15:17AM -0700, Andrew Morton wrote: > > On Tue, 22 May 2007 09:07:37 -0700 > > Stephane Eranian <[EMAIL PROTECTED]> wrote: > > > > > Andrew, > > > > > > On Tue, May 22, 2007 at 09:02:10AM -0700, Andrew Morton wrote: > > > > On Tue, 22 May 2007 05:47:13 -0700 > > > > Stephane Eranian <[EMAIL PROTECTED]> wrote: > > > > > > > > > Hello, > > > > > > > > > > For perfmon, we need a couple of TIF bits. It seems that with > > > > > 2.6.22-rc2 > > > > > there is now a TIF_RESTORE_SIGMASK which uses the last remaining bit > > > > > in the > > > > > first 7 bits of the thread flag. Many architectures, including IA-64, > > > > > rely > > > > > on the fact that some of the TIF flags (TIF_ALL_WORKMASK or > > > > > TIF_ALL_WORK) > > > > > tested on kernel exit reside in the low 8-bit or 7-bit because they > > > > > use > > > > > instructions (such as add r1=imm8,r2 on IA-64) which operate on 8 or > > > > > 7 bit > > > > > immediate. > > > > > > > > > > On IA-64, adding that one perfmon flag (as bit 7) would cause some > > > > > restructuring in the kernel exit path but also in all the lightweight > > > > > syscall > > > > > handlers. > > > > > > > > > > I looked at all the low order TIF flags and found that > > > > > TIF_NOTIFY_RESUME > > > > > was never set nor used anywhere in any architecture. Is that really > > > > > the case? > > > > > > > > > > If so, we could get rid of it and free up one low-order TIF bit. > > > > > > > > > > > > > My grepping argees with yours. The only place where TIF_NOTIFY_RESUME > > > > gets > > > > altered is in ./arch/ia64/kernel/perfmon.c. > > > > > > Yes, and that is with the old IA-64 code. In the new one I used a > > > dedicated > > > TIF flag. > > > > > > Shall we just get rid of the flag, then? > > > > > > > I'd say so, yes. > > Do you want a single patch or small patches broken-down by arch (and there > are many...)? One patch is OK for this, thanks. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
