Re: Write watchpoints

[Jie Zhang <jie.zhang@analog.com>]

Guillaume MENANT wrote:
> I'm trying to implement watchpoints management in my software but it doesn't
> works. For a write watchpoint at 0x800000A4,  GDB sets it (Z2) and then the
> watchpoint triggers on my board (just before executing the asm instruction
> which modifies the 0x800000A4 address), so I send back the answer
> T05watch800000A4 to GDB before effectively writing to the 0x800000A4
> address. Then GDB reads the system registers (G), reads at the 0x800000A4
> address, unsets the watchpoint, reads at the 0x800000A4 address, re-sets the
> watchpoint (at the same address) and make a continue. Then the watchpoint
> triggers again immediately  because the instruction modifying the 0x800000A4
> address has not been executed before.
> 
> What is the problem with this GDB flow ? What can I do ?
> 
It seems that gdb expects the address of the next instruction to
watchpoint when watchpoint is triggered. Blackfin is similar to your
target: the watchpoint is triggered just when the address appears on the
address bus and before the write happens. We just do a single step and
send the address of the next instruction of the one which triggers the 
watchpoint to gdb.


Jie