kqemu locking my machine hard on amd64 smp, with most recent patches

[Juergen Lock]

On Fri, May 16, 2008 at 06:07:32PM -0400, Todd Wasson wrote:
> Using -m 256 doesn't help, though interestingly 1.3.0.p11_5 crashes (but 
> doesn't take down the machine) with -m 1536 but is fine with -m 256.  
> 1.3.0.p11_6 hangs the machine regardless, though.
> 
> I haven't been using -soundhw at all recently, but yes, I do actually have 
> sound on the host.
> 
> Lowering hw.physmem to 2GB and using -m 256 still results in a hang.
> 
> I'm going to keep these and try the max_locked_pages changes that Bakul 
> Shah suggested.  I'll post the results to the list.
> 
> Thanks again.

OK can you try the following kernel patch with the latest kqemu (also at
	http://people.freebsd.org/~nox/qemu/patch-sys-amd64-seperate-gdt.txt
- untested because my amd64 smp box is in the middle of a portupgrade that
was long overdue...)

Index: src/sys/amd64/amd64/mp_machdep.c
===================================================================
RCS file: /home/ncvs/src/sys/amd64/amd64/mp_machdep.c,v
retrieving revision 1.287.2.2
diff -u -p -u -r1.287.2.2 mp_machdep.c
--- src/sys/amd64/amd64/mp_machdep.c	28 Nov 2007 23:24:06 -0000	1.287.2.2
+++ src/sys/amd64/amd64/mp_machdep.c	18 May 2008 13:45:32 -0000
@@ -457,10 +457,18 @@ init_secondary(void)
 	common_tss[cpu].tss_iobase = sizeof(struct amd64tss);
 	common_tss[cpu].tss_ist1 = (long)&doublefault_stack[PAGE_SIZE];
 
+	/* Use a seperate gdt for each cpu because the tss differs
+	 * This avoids complications for e.g. virtualization software
+	 * that needs to reload the task register and otherwise would
+	 * then end up using the last cpu's tss on others
+	 */
+	bcopy(&gdt[0], &gdt[NGDT * cpu], NGDT * sizeof(gdt[0]));
+
 	gdt_segs[GPROC0_SEL].ssd_base = (long) &common_tss[cpu];
 	ssdtosyssd(&gdt_segs[GPROC0_SEL],
-	   (struct system_segment_descriptor *)&gdt[GPROC0_SEL]);
+	   (struct system_segment_descriptor *)&gdt[NGDT * cpu + GPROC0_SEL]);
 
+	r_gdt.rd_base =  (long) &gdt[NGDT * cpu];
 	lgdt(&r_gdt);			/* does magic intra-segment return */
 
 	/* Get per-cpu data */