[PATCH v2] arm64: Support hard limit of cpu count by nr_cpus

On 2016/8/8 20:52, Suzuki K Poulose wrote:

On 08/08/16 12:28, Kefeng Wang wrote:

quoted

On 2016/8/8 18:50, Suzuki K Poulose wrote:

quoted

On 08/08/16 07:05, Kefeng Wang wrote:

quoted

Enable the hard limit of cpu count by set boot options nr_cpus=x
on arm64, and show a better warning when cpu number exceeds the limit.

Reported-by: Shiyuan Hu <redacted>
Signed-off-by: Kefeng Wang <redacted>
---

Changed since v1:
- clip cpu number in smp_init_cpus suggested-by Will and Suzuki, and update
  the warning.

 arch/arm64/kernel/smp.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/arch/arm64/kernel/smp.c b/arch/arm64/kernel/smp.c
index 76a6d92..cbfc31c 100644
--- a/arch/arm64/kernel/smp.c
+++ b/arch/arm64/kernel/smp.c

@@ -661,9 +661,9 @@ void __init smp_init_cpus(void)
         acpi_table_parse_madt(ACPI_MADT_TYPE_GENERIC_INTERRUPT,
                       acpi_parse_gic_cpu_interface, 0);

-    if (cpu_count > NR_CPUS)
-        pr_warn("no. of cores (%d) greater than configured maximum of %d - clipping\n",
-            cpu_count, NR_CPUS);
+    if (cpu_count > nr_cpu_ids)
+        pr_warn("%d cores exceeds configured maximum of %d - clipping\n",
+            cpu_count, nr_cpu_ids);

I think we should leave the message as it was, and is better than what you have
changed it to.

The old message is OF only and the old logic shows message when the first cpu number greater than NR_CPUS.

I think you misunderstood "of" (as in plain english) with OF (as in Open Firmware). To avoid
the confusion, how about making it :

"Number of cores (%d) exceeds configured maximum of %d - clipping\n" ?

Er, I do misunderstood it, my bad, will use this one, thanks :)

Kefeng

Certainly a message like :

"5 cores exceeds configured maximum of %d..." doesn't look nice.


Suzuki

quoted

But now the cpu_count is the total cpu counts(get from DT or ACPI), so I change the message.

quoted

With that change,

Reviewed-by: Suzuki K Poulose <suzuki.poulose@arm.com>


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