On 15/09/2015 20:45, Richard Henderson wrote:
> Best guess, since I can't find any code that actually uses them.
> Linux actively turns them off at boot...
I've sent a kvm-unit-tests patch to test debug extensions. It shows
that debug extensions work, but the following needs to be squashed in
patch 4:
diff --git a/target-i386/bpt_helper.c b/target-i386/bpt_helper.c
index c258598..b24e446 100644
--- a/target-i386/bpt_helper.c
+++ b/target-i386/bpt_helper.c
@@ -134,14 +134,14 @@ void cpu_x86_update_dr7(CPUX86State *env, uint32_t
new_dr7)
int mod = ((old_dr7 | old_dr7 * 2) ^ (new_dr7 | new_dr7 * 2)) & 0xff;
for (i = 0; i < DR7_MAX_BP; i++) {
- if (mod & (2 << i * 2)) {
- /* We know that register i has changed enable state;
- recheck what that state should be and apply. */
- if (hw_breakpoint_enabled(new_dr7, i)) {
- iobpt |= hw_breakpoint_insert(env, i);
- } else {
- hw_breakpoint_remove(env, i);
- }
+ if ((mod & (2 << i * 2)) && !hw_breakpoint_enabled(new_dr7, i)) {
+ hw_breakpoint_remove(env, i);
+ }
+ }
+ env->dr[7] = new_dr7 | DR7_FIXED_1;
+ for (i = 0; i < DR7_MAX_BP; i++) {
+ if (mod & (2 << i * 2) && hw_breakpoint_enabled(new_dr7, i)) {
+ iobpt |= hw_breakpoint_insert(env, i);
} else if (hw_breakpoint_type(new_dr7, i) == DR7_TYPE_IO_RW
&& hw_breakpoint_enabled(new_dr7, i)) {
iobpt |= HF_IOBPT_MASK;
Otherwise, hw_breakpoint_insert doesn't work because it expects to
see an updated env->dr[7].
There are a couple other issues that the tests expose, but they are
not regressions so I will send patches later.
Paolo
