parisc: Use fast cr16 clocksource with qemu

PATCH New Helge Deller 1 participant 1 message Jan 8, 2018 PA-RISC architecture

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Helge Deller

author maintainer

2018-01-08 20:36 UTC #0 lore raw

PATCH 1/1 parisc: Use fast cr16 clocksource with qemu

When booted in qemu, the (emulated) cr16 clocksources are monotonic and syncronized, so they can be used as stable clocksources.

Signed-off-by Helge Deller <[email protected]>

arch/parisc/include/asm/processor.h +2 -0

index 0e6ab6e4a4e9..2dbe5580a1a4 100644
@@ -316,6 +316,8 @@ extern int _parisc_requires_coherency;
 #define parisc_requires_coherency()	(0)
 #endif
 
+extern int running_on_qemu;
+
 #endif /* __ASSEMBLY__ */
 
 #endif /* __ASM_PARISC_PROCESSOR_H */

arch/parisc/kernel/time.c +1 -1

index 4b8fd6dc22da..68e88e5c0898 100644
@@ -248,7 +248,7 @@ static int __init init_cr16_clocksource(void)
 	 * different sockets, so mark them unstable and lower rating on
 	 * multi-socket SMP systems.
 	 */
-	if (num_online_cpus() > 1) {
+	if (num_online_cpus() > 1 && !running_on_qemu) {
 		int cpu;
 		unsigned long cpu0_loc;
 		cpu0_loc = per_cpu(cpu_data, 0).cpu_loc;