From 9225d739e7f6ec8d2139f79c3d2e3282cc725364 Mon Sep 17 00:00:00 2001 From: Peter Maydell Date: Tue, 15 Apr 2014 19:18:41 +0100 Subject: [PATCH] target-arm: Don't mention PMU in debug feature register Suppress the ID_AA64DFR0_EL1 PMUVer field, even if the CPU specific value claims that it exists. QEMU doesn't currently implement it, and not advertising it prevents the guest from trying to use it and getting UNDEFs on unimplemented registers. Signed-off-by: Peter Maydell Reviewed-by: Peter Crosthwaite --- This is arguably a hack, but otherwise Linux tries to prod half a dozen PMU sysregs. --- target-arm/helper.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) diff --git a/target-arm/helper.c b/target-arm/helper.c index 4b6c1b6..62f7fd3 100644 --- a/target-arm/helper.c +++ b/target-arm/helper.c @@ -2036,7 +2036,12 @@ void register_cp_regs_for_features(ARMCPU *cpu) { .name = "ID_AA64DFR0_EL1", .state = ARM_CP_STATE_AA64, .opc0 = 3, .opc1 = 0, .crn = 0, .crm = 5, .opc2 = 0, .access = PL1_R, .type = ARM_CP_CONST, - .resetvalue = cpu->id_aa64dfr0 }, + /* We mask out the PMUVer field, beacuse we don't currently + * implement the PMU. Not advertising it prevents the guest + * from trying to use it and getting UNDEFs on registers we + * don't implement. + */ + .resetvalue = cpu->id_aa64dfr0 & ~0xf00 }, { .name = "ID_AA64DFR1_EL1", .state = ARM_CP_STATE_AA64, .opc0 = 3, .opc1 = 0, .crn = 0, .crm = 5, .opc2 = 1, .access = PL1_R, .type = ARM_CP_CONST, -- 2.7.4