Messages in this thread | | | Date | Tue, 26 Apr 2016 15:50:46 +0100 | From | Will Deacon <> | Subject | Re: [PATCH v5 0/5] arm64: Fix behavior of maxcpus=n |
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On Tue, Apr 26, 2016 at 03:48:55PM +0100, Suzuki K Poulose wrote: > This series is an attempt at fixing the maxcpus=n behavior > on arm64. So far we have disabled hotplugging a CPU > n, > when maxcpus=n is in effect, due to following reasons. > > 1) Possible cpu feature incompatibilities with the new CPU > in heterogeneous systems. > 2) New CPU requiring an errata work around which was not detected > (and the code patched in) at boot time. > 3) Failure to initialise the PMU in case the supported CPUs are > not online while probing the PMU. > > (1) has been mostly solved with our early CPU feature verification > support. This series tries to address (2) & (3). > > (2) is solved by iterating over the known erratas and checking if > the new CPU requires an errata not set in the cpu_hwcaps, failing > which, we kill the CPU. We plan to fix this properly by retaining > the CPU errata work arounds and apply the required at runtime. > > (3) is ignored and will not be fixed as there is no reliable way of > knowing if there would be a CPU that will be online to support the > PMU. > > In the process, also restores the capability to check GIC interface settings > by the firmware on individual CPUs. > > Tested on Juno with maxcpus=2 (enables A57 cores and A57-PMU) and > maxcpus=1 (disables both A57 cores and A57-PMU). > > This series applies on aarch64/for-next/core : > > The tree is available here : > git://linux-arm.org/linux-skp.git maxcpus/v5 > > Changes since V4: > - Address Catalin's comments > - Rebased to aarch64 for-next/core > - Add Reviewed/Acked bys.
I merged this yesterday onto for-next/core. Please can you check that I fixed everything up that you expected?
Will
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