diff mbox

arm64: Support hard limit of cpu count by nr_cpus

Message ID 1470377035-1591-1-git-send-email-wangkefeng.wang@huawei.com
State New
Headers show

Commit Message

Kefeng Wang Aug. 5, 2016, 6:03 a.m. UTC
Enable the hard limit of cpu count by nr_cpus on arm64.
The code is borrowed from MIPS.

Reported-by: Shiyuan Hu <hushiyuan@huawei.com>
Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>

---
 arch/arm64/kernel/setup.c | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

-- 
1.7.12.4


_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

Comments

Will Deacon Aug. 5, 2016, 8:32 a.m. UTC | #1
On Fri, Aug 05, 2016 at 02:03:55PM +0800, Kefeng Wang wrote:
> Enable the hard limit of cpu count by nr_cpus on arm64.

> The code is borrowed from MIPS.

> 

> Reported-by: Shiyuan Hu <hushiyuan@huawei.com>

> Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>

> ---

>  arch/arm64/kernel/setup.c | 16 ++++++++++++++++

>  1 file changed, 16 insertions(+)

> 

> diff --git a/arch/arm64/kernel/setup.c b/arch/arm64/kernel/setup.c

> index 536dce2..597b777 100644

> --- a/arch/arm64/kernel/setup.c

> +++ b/arch/arm64/kernel/setup.c

> @@ -224,6 +224,21 @@ static void __init request_standard_resources(void)

>  

>  u64 __cpu_logical_map[NR_CPUS] = { [0 ... NR_CPUS-1] = INVALID_HWID };

>  

> +static void __init prefill_possible_map(void)

> +{

> +	int i, possible = num_possible_cpus();

> +

> +	if (possible > nr_cpu_ids)

> +		possible = nr_cpu_ids;

> +

> +	for (i = 0; i < possible; i++)

> +		set_cpu_possible(i, true);

> +	for (; i < NR_CPUS; i++)

> +		set_cpu_possible(i, false);

> +

> +	nr_cpu_ids = possible;

> +}


Shouldn't we just avoid marking those CPUs as possible in smp_cpu_setup,
rather than rewriting things later on?

Also, can you explain exactly what functionality is missing at the moment,
please? I assume it's the nr_cpus= option not working correctly?

Will

_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
diff mbox

Patch

diff --git a/arch/arm64/kernel/setup.c b/arch/arm64/kernel/setup.c
index 536dce2..597b777 100644
--- a/arch/arm64/kernel/setup.c
+++ b/arch/arm64/kernel/setup.c
@@ -224,6 +224,21 @@  static void __init request_standard_resources(void)
 
 u64 __cpu_logical_map[NR_CPUS] = { [0 ... NR_CPUS-1] = INVALID_HWID };
 
+static void __init prefill_possible_map(void)
+{
+	int i, possible = num_possible_cpus();
+
+	if (possible > nr_cpu_ids)
+		possible = nr_cpu_ids;
+
+	for (i = 0; i < possible; i++)
+		set_cpu_possible(i, true);
+	for (; i < NR_CPUS; i++)
+		set_cpu_possible(i, false);
+
+	nr_cpu_ids = possible;
+}
+
 void __init setup_arch(char **cmdline_p)
 {
 	pr_info("Boot CPU: AArch64 Processor [%08x]\n", read_cpuid_id());
@@ -285,6 +300,7 @@  void __init setup_arch(char **cmdline_p)
 	cpu_read_bootcpu_ops();
 	smp_init_cpus();
 	smp_build_mpidr_hash();
+	prefill_possible_map();
 
 #ifdef CONFIG_VT
 #if defined(CONFIG_VGA_CONSOLE)