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ARM: Permit any ARMv6K CPU to read the MVFR0 and MVFR1 VFP registers. 

This patch replaces the ARM_FEATURE_VFP3 test when reading MVFR registers
with a test for a new feature flag ARM_FEATURE_MVFR, and sets this feature
for all ARMv6K cores (ARM1156 is not a v6K core, yet supports MVFR; qemu
does not support ARM1156 at this time.)

MVFR0 and MVFR1 were introduced in ARM1136JF-S r1p0 (ARMv6K, VFPv2) and are
present in ARM1156T2F-S (non-v6K), ARM1176JZF-S, ARM11MPCore and newer cores.
Reference: ARM DDI 0211H, 0290G, 0301H, 0360E.
http://infocenter.arm.com/help/index.jsp?topic=/com.arm.doc.ddi0211h/Ffbefjag.html

Without this change, the linux kernel will not boot with VFP support enabled
under ARM1176 system emulation, due to the unconditional use of MVFR1 at the
end of vfp_init() in arch/arm/vfp/vfpmodule.c:

  VFP support v0.3: implemetor 41 architecture 1 part 20 variant b rev 5
  Internal error: Oops - undefined instruction: 0 [#1]

Signed-off-by: Andrew Towers <atowers@gmail.com>
Reviewed-by: Andreas Färber <afaerber@suse.de>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
This commit is contained in:
Andrew Towers 2012-03-29 02:41:08 +00:00 committed by Peter Maydell
parent dec9c2d430
commit 06ed5d66f7
3 changed files with 3 additions and 1 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

1
target-arm/cpu.h
View File

@ -382,6 +382,7 @@ enum arm_features {
ARM_FEATURE_ARM_DIV, /* divide supported in ARM encoding */
ARM_FEATURE_VFP4, /* VFPv4 (implies that NEON is v2) */
ARM_FEATURE_GENERIC_TIMER,
ARM_FEATURE_MVFR, /* Media and VFP Feature Registers 0 and 1 */
};
static inline int arm_feature(CPUARMState *env, int feature)

1
target-arm/helper.c
View File

@ -254,6 +254,7 @@ static void cpu_reset_model_id(CPUARMState *env, uint32_t id)
}
if (arm_feature(env, ARM_FEATURE_V6K)) {
set_feature(env, ARM_FEATURE_V6);
set_feature(env, ARM_FEATURE_MVFR);
}
if (arm_feature(env, ARM_FEATURE_V6)) {
set_feature(env, ARM_FEATURE_V5);

2
target-arm/translate.c
View File

@ -2906,7 +2906,7 @@ static int disas_vfp_insn(CPUARMState * env, DisasContext *s, uint32_t insn)
case ARM_VFP_MVFR0:
case ARM_VFP_MVFR1:
if (IS_USER(s)
|| !arm_feature(env, ARM_FEATURE_VFP3))
|| !arm_feature(env, ARM_FEATURE_MVFR))
return 1;
tmp = load_cpu_field(vfp.xregs[rn]);
break;