Re: Hardware watchpoint for read

[Xin Tong <xerox dot time dot tech at gmail dot com>]

On Tue, Apr 24, 2012 at 9:09 AM, Luis Gustavo <luis_gustavo@mentor.com> wrote:
> Hi,
>
>
> On 04/24/2012 10:02 AM, Xin Tong wrote:
>>
>> Hello
>>
>> I am wondering that can gdb insert hardware watch point for read to
>> the watched memory ? can other debugger do that ? is it supported in
>> hardware watchpoint ?
>>
>> Thanks
>>
>> Xin
>>
>
> Read watchpoints are hard to implement as soft-watchpoints, so they're
> usually implemented as hardware watchpoints.

software write watchpoint is easier to implement ? do not software
watchpoint need to watch all memory accesses (read and write) to a
memory location in software ?

>
> If a debugger knows how to properly set the bits in the hardware, either
> through ptrace or other means, it can configure a read/write/read-write
> watchpoint. Depends on hardware support really.

do you know whether this is supported on the x86 chips ? is thee a way
to try this out in gdb ?

>
> Regards,
> Luis