arm64: Honor nosmp kernel command line option

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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 44dbcc93ab ("arm64: Fix behavior of maxcpus=N") fixed the
behavior for maxcpus >= 1, but broke maxcpus = 0.

Fixes: 44dbcc93ab ("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>

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Suzuki K Poulose 2016-07-21 11:15:27 +01:00 • committed by Catalin Marinas

parent 9113c2aa05

commit e75118a7b5

1 changed files with 7 additions and 0 deletions

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arch/arm64/kernel/smp.c

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