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[Qemu-devel] [PATCH] target-arm: Implement a minimal set of cp14 debug r
From: |
Peter Maydell |
Subject: |
[Qemu-devel] [PATCH] target-arm: Implement a minimal set of cp14 debug registers |
Date: |
Tue, 22 Feb 2011 18:19:43 +0000 |
Newer ARM kernels try to probe for whether the CPU has hardware breakpoint
support. For this to work QEMU has to implement a minimal set of the cp14
debug registers. The architecture requires v7 cores to implement debug
and so there is no defined way to report its absence; however in practice
returning a zero DBGDIDR (ie with a reserved value for "debug architecture
version") should cause well-written hw debug users to do the right thing.
We also implement DBGDRAR and DBGDSAR as RAZ, indicating no memory mapped
debug components.
Signed-off-by: Peter Maydell <address@hidden>
---
target-arm/translate.c | 28 ++++++++++++++++++++++++++++
1 files changed, 28 insertions(+), 0 deletions(-)
diff --git a/target-arm/translate.c b/target-arm/translate.c
index dbd958b..d05859d 100644
--- a/target-arm/translate.c
+++ b/target-arm/translate.c
@@ -5769,6 +5769,34 @@ static int disas_cp14_read(CPUState * env, DisasContext
*s, uint32_t insn)
int rt = (insn >> 12) & 0xf;
TCGv tmp;
+ /* Minimal set of debug registers, since we don't support debug */
+ if (op1 == 0 && crn == 0 && op2 == 0) {
+ switch (crm) {
+ case 0:
+ /* DBGDIDR: just RAZ. In particular this means the
+ * "debug architecture version" bits will read as
+ * a reserved value, which should cause Linux to
+ * not try to use the debug hardware.
+ */
+ tmp = tcg_const_i32(0);
+ store_reg(s, rt, tmp);
+ return 0;
+ case 1:
+ case 2:
+ /* DBGDRAR and DBGDSAR: v7 only. Always RAZ since we
+ * don't implement memory mapped debug components
+ */
+ if (ENABLE_ARCH_7) {
+ tmp = tcg_const_i32(0);
+ store_reg(s, rt, tmp);
+ return 0;
+ }
+ break;
+ default:
+ break;
+ }
+ }
+
if (arm_feature(env, ARM_FEATURE_THUMB2EE)) {
if (op1 == 6 && crn == 0 && crm == 0 && op2 == 0) {
/* TEECR */
--
1.7.1
- [Qemu-devel] [PATCH] target-arm: Implement a minimal set of cp14 debug registers,
Peter Maydell <=