Re: Unexpected variation in SYS_ID_AA64MMFR0_EL1
From: Suzuki K Poulose <suzuki.poulose@arm.com>
Date: 2018-12-05 10:18:03
On 03/12/2018 15:32, Catalin Marinas wrote:
On Fri, Nov 30, 2018 at 01:23:28PM +0000, Suzuki K. Poulose wrote:quoted
On 30/11/2018 13:12, Ard Biesheuvel wrote:quoted
On Fri, 30 Nov 2018 at 13:15, Marc Gonzalez [off-list ref] wrote:quoted
On an APQ8098-based system, for cores 4-7 (little cores?), the kernel prints: [ 0.179055] CPU features: SANITY CHECK: Unexpected variation in SYS_ID_AA64MMFR0_EL1. Boot CPU: 0x00000000001122, CPU4: 0x00000000101122 TGran16, [23:20] Support for 16KB memory translation granule size: 0x1 Indicates that the 16KB granule is supported. Since this is a pr_warn, I get the feeling something is not quite right. Is there something to fix? Is it a problem that the big and little cores don't support exactly the same granule sizes?That looks like a false positive to me. We should only care about the page size we are running with.Unless you run a VM, which is going to use 16K translation. But this may be fine with the current kernels, where we emulate the SANITISED registers for the guests.I think that's sanitised now for KVM, so we could downgrade the feature to FTR_NONSTRICT.
Yes, the only caveat is we must make sure that the patch somehow reflect the KVM changes to prevent backports assuming that it is safe to change them without the KVM bits. I will cook something up, along with the other feature bits. Cheers Suzuki _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel