The best place to look at how these registers are programmed is the arm TRM - http://infocenter.arm.com
From: email@example.com [mailto:firstname.lastname@example.org] On Behalf Of Pieter Conradie
Sent: 27 May 2008 10:45
Subject: Re: [Openocd-development] Setting a watchpoint to break when writing a specific value to a specific addressNotice
The mask should be set to 0x0000000 when trying to halt the CPU when a specific value is written, e.g.
wp 0x00200098 4 w 0xaabbccdd 0x00000000
From: Pieter Conradie
Sent: 22 May 2008 08:34 AM
Subject: Setting a watchpoint to break when writing a specific value to a specific address
The target I am trying to debug is an Atmel AT91SAM7S256 (arm7tdmi core). The OpenOCD revision is 657. The syntax for setting a watch point is:
wp set watchpoint <address> <length> <r/w/a> [value] [mask]
I want OpenOCD to only break when a specific value (0xaabbccdd) is written to a specific address (0x00200098). I used the following command:
wp 0x00200098 4 w 0xaabbccdd
By querying the watchpoints (using “wp”) the following is reported (note that the word “mask” is used twice):
address: 0x00200098, mask: 0x00000004, r/w/a: 1, value: 0xaabbccdd, mask: 0xffffffff
The problem is that OpenOCD breaks when ANY value is written to the specified address. Am I missing something?
Thanks for your time!
P.S. I am trying to find the cause of a nasty Prefetch Abort because of a nested interrupt handler and the only way is using this feature.
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