This is a rough first cut at handshaking with the secondary processors.
Once we get this right, they will wait on a shared variable, build a
stack, and start running C code proper. I am posting this now because I
want to make sure we get the register flushes and memory barriers
correct. Any comments?
The code prints output like this on a JS21:
spinning up secondary processor #1: ping = 0: pong = 1
spinning up secondary processor #2: ping = 0: pong = 2
spinning up secondary processor #3: ping = 0: pong = 3
---
boot_of.c | 33 ++++++++++++++++++++++++++++++++-
powerpc64/exceptions.S | 23 +++++++++++++++++++----
2 files changed, 51 insertions(+), 5 deletions(-)
diff -r 058f2e27476d xen/arch/powerpc/boot_of.c
--- a/xen/arch/powerpc/boot_of.c Mon Aug 07 17:49:16 2006 -0500
+++ b/xen/arch/powerpc/boot_of.c Wed Aug 09 23:08:03 2006 -0400
@@ -42,6 +42,7 @@ static char builtin_cmdline[COMMAND_LINE
__attribute__((section("__builtin_cmdline"))) = CMDLINE;
extern struct ns16550_defaults ns16550;
+extern unsigned long __spin_ack;
#undef OF_DEBUG
@@ -956,7 +957,37 @@ static int __init boot_of_cpus(void)
/* FIXME: should not depend on the boot CPU bring the first child */
cpu = of_getpeer(cpu);
while (cpu > 0) {
- of_start_cpu(cpu, (ulong)spin_start, 0);
+ unsigned int cpuid;
+ unsigned long ping, pong, now, then, timeout;
+ unsigned long *ack = (unsigned long *)&__spin_ack;
+
+ result = of_getprop(cpu, "reg", &cpuid, sizeof(cpuid));
+ if (result == OF_FAILURE) of_panic("cpuid lookup failed\n");
+
+ of_printf("spinning up secondary processor #%d: ", cpuid);
+
+ *ack = 0x0;
+ ping = *ack;
+ of_printf("ping = %lx: ", ping);
+
+ mb();
+ of_start_cpu(cpu, (ulong)spin_start, cpuid);
+
+ then = mftb();
+ timeout = then + 1024;
+ do {
+ now = mftb();
+ if (now >= timeout) {
+ of_printf("SKIPPING: ");
+ pong = ~0x0;
+ break;
+ }
+
+ mb();
+ pong = *ack;
+ } while (pong == ping);
+ of_printf("pong = %lx\n", pong);
+
cpu = of_getpeer(cpu);
}
return 1;
diff -r 058f2e27476d xen/arch/powerpc/powerpc64/exceptions.S
--- a/xen/arch/powerpc/powerpc64/exceptions.S Mon Aug 07 17:49:16 2006 -0500
+++ b/xen/arch/powerpc/powerpc64/exceptions.S Wed Aug 09 21:41:16 2006 -0400
@@ -178,6 +178,25 @@ zero:
li r0, 0x0 /* exception vector for GDB stub */
bctr
+/* Begin secondary processor spin and ack logic. */
+ .globl __spin_ack
+__spin_ack:
+ .llong 0x0
+
+ .globl spin_start
+spin_start:
+ /* Our physical cpu number is passed in r3. */
+ mr r24, r3
+ lis r25, __spin_ack@highest
+ ori r25, r25, __spin_ack@higher
+ rldicr r25, r25, 32, 31
+ oris r25, r25, __spin_ack@h
+ ori r25, r25, __spin_ack@l
+ stdu r24, 0(r25)
+ sync
+ b .
+
+/* Begin exception handlers. */
. = 0x100 # System Reset
ex_reset:
/* XXX thread initialization */
@@ -513,7 +532,3 @@ _GLOBAL(sleep)
isync
mtmsrd r3
blr
-
- .globl spin_start
-spin_start:
- b .
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