Re: [Qemu-devel] [PATCH 0/8] target-i386: Implement debug extensions

[Paolo Bonzini <pbonzini@redhat.com>]

On 21/09/2015 16:05, Eduardo Habkost wrote:
> On Mon, Sep 21, 2015 at 02:05:52PM +0200, Paolo Bonzini wrote:
>> 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;
> 
> Thanks! If that's the only change needed in the series, I can squash it
> when applying. I just need your Signed-off-by line.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

:)

but perhaps wait a little for Richard to chime in.

Paolo