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authorDavid S. Miller <davem@davemloft.net>2005-05-23 15:52:08 -0700
committerDavid S. Miller <davem@davemloft.net>2005-05-23 15:52:08 -0700
commit816242da3735957bee99aeba40aa60c4f120a101 (patch)
treec5a1092a52911143b0c4f9bc4257c1dbafbb8bdd /arch
parentab3fc403633c38aef5ef48844f8e5dbfee7c34f8 (diff)
[SPARC64]: Add boot option to force UltraSPARC-III P-Cache on.
Older UltraSPARC-III chips have a P-Cache bug that makes us disable it by default at boot time. However, this does hurt performance substantially, particularly with memcpy(), and the bug is _incredibly_ obscure. I have never seen it triggered in practice, ever. So provide a "-P" boot option that forces the P-Cache on. It taints the kernel, so if it does trigger and cause some data corruption or OOPS, we will find out in the logs that this option was on when it happened. Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'arch')
-rw-r--r--arch/sparc64/kernel/setup.c11
-rw-r--r--arch/sparc64/kernel/smp.c3
-rw-r--r--arch/sparc64/kernel/traps.c19
3 files changed, 33 insertions, 0 deletions
diff --git a/arch/sparc64/kernel/setup.c b/arch/sparc64/kernel/setup.c
index 12c3d84b746..b7e6a91952b 100644
--- a/arch/sparc64/kernel/setup.c
+++ b/arch/sparc64/kernel/setup.c
@@ -383,6 +383,17 @@ static void __init process_switch(char c)
/* Use PROM debug console. */
register_console(&prom_debug_console);
break;
+ case 'P':
+ /* Force UltraSPARC-III P-Cache on. */
+ if (tlb_type != cheetah) {
+ printk("BOOT: Ignoring P-Cache force option.\n");
+ break;
+ }
+ cheetah_pcache_forced_on = 1;
+ add_taint(TAINT_MACHINE_CHECK);
+ cheetah_enable_pcache();
+ break;
+
default:
printk("Unknown boot switch (-%c)\n", c);
break;
diff --git a/arch/sparc64/kernel/smp.c b/arch/sparc64/kernel/smp.c
index 6dff06a44e7..e5b9c7a2778 100644
--- a/arch/sparc64/kernel/smp.c
+++ b/arch/sparc64/kernel/smp.c
@@ -123,6 +123,9 @@ void __init smp_callin(void)
smp_setup_percpu_timer();
+ if (cheetah_pcache_forced_on)
+ cheetah_enable_pcache();
+
local_irq_enable();
calibrate_delay();
diff --git a/arch/sparc64/kernel/traps.c b/arch/sparc64/kernel/traps.c
index 56b203a2af6..a9f4596d7c2 100644
--- a/arch/sparc64/kernel/traps.c
+++ b/arch/sparc64/kernel/traps.c
@@ -421,6 +421,25 @@ asmlinkage void cee_log(unsigned long ce_status,
}
}
+int cheetah_pcache_forced_on;
+
+void cheetah_enable_pcache(void)
+{
+ unsigned long dcr;
+
+ printk("CHEETAH: Enabling P-Cache on cpu %d.\n",
+ smp_processor_id());
+
+ __asm__ __volatile__("ldxa [%%g0] %1, %0"
+ : "=r" (dcr)
+ : "i" (ASI_DCU_CONTROL_REG));
+ dcr |= (DCU_PE | DCU_HPE | DCU_SPE | DCU_SL);
+ __asm__ __volatile__("stxa %0, [%%g0] %1\n\t"
+ "membar #Sync"
+ : /* no outputs */
+ : "r" (dcr), "i" (ASI_DCU_CONTROL_REG));
+}
+
/* Cheetah error trap handling. */
static unsigned long ecache_flush_physbase;
static unsigned long ecache_flush_linesize;