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| author | Suzuki K Poulose <suzuki.poulose@arm.com> | 2016-07-21 12:15:27 +0200 |
|---|---|---|
| committer | Catalin Marinas <catalin.marinas@arm.com> | 2016-07-21 17:48:37 +0200 |
| commit | e75118a7b581b19b08282c7819c1ec6f68b91b79 (patch) | |
| tree | b2f9b83d8f4627a243c20001ec064e27aad10a01 /arch/arm64/kernel/smp.c | |
| parent | arm64: Fix incorrect per-cpu usage for boot CPU (diff) | |
| download | linux-e75118a7b581b19b08282c7819c1ec6f68b91b79.tar.xz linux-e75118a7b581b19b08282c7819c1ec6f68b91b79.zip | |
arm64: Honor nosmp kernel command line option
Passing "nosmp" should boot the kernel with a single processor, without
provision to enable secondary CPUs even if they are present. "nosmp" is
implemented by setting maxcpus=0. At the moment we still mark the secondary
CPUs present even with nosmp, which allows the userspace to bring them
up. This patch corrects the smp_prepare_cpus() to honor the maxcpus == 0.
Commit 44dbcc93ab67145 ("arm64: Fix behavior of maxcpus=N") fixed the
behavior for maxcpus >= 1, but broke maxcpus = 0.
Fixes: 44dbcc93ab67 ("arm64: Fix behavior of maxcpus=N")
Cc: <stable@vger.kernel.org> # 4.7+
Cc: Will Deacon <will.deacon@arm.com>
Cc: James Morse <james.morse@arm.com>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Acked-by: Mark Rutland <mark.rutland@arm.com>
[catalin.marinas@arm.com: updated code comment]
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Diffstat (limited to 'arch/arm64/kernel/smp.c')
| -rw-r--r-- | arch/arm64/kernel/smp.c | 7 |
1 files changed, 7 insertions, 0 deletions
diff --git a/arch/arm64/kernel/smp.c b/arch/arm64/kernel/smp.c index 298dd745651e..490db85dec23 100644 --- a/arch/arm64/kernel/smp.c +++ b/arch/arm64/kernel/smp.c @@ -693,6 +693,13 @@ void __init smp_prepare_cpus(unsigned int max_cpus) smp_store_cpu_info(smp_processor_id()); /* + * If UP is mandated by "nosmp" (which implies "maxcpus=0"), don't set + * secondary CPUs present. + */ + if (max_cpus == 0) + return; + + /* * Initialise the present map (which describes the set of CPUs * actually populated at the present time) and release the * secondaries from the bootloader. |