On Thu, Feb 18, 2010 at 09:44:24AM -0500, John Baldwin wrote: > On Wednesday 17 February 2010 11:07:36 pm Anderson Eduardo wrote: > > > > Hello Folks, > > > > First, I'm starting in the world of the debugging FreeBSD Kernel and, I > don't know to use kgdb and ddb properly and, I need set breakpoints using > debug register. Those breakpoints in the all tasks. > > This last might be tricky to accomplish because cpu_switch() will swap out > the debug registers if a thread is using them. However, you can easily > manage hardware breakpoints from ddb using the 'hwatch' command. It is > documented in ddb(4). kgdb doesn't support setting hardware watch points > it seems. Note that you can try to use 'db_md_set_watchpoint()' from your > kernel module (with DDB compiled into your kernel) if you want to set the > address progammatically rather than via the 'hwatch' command in ddb.
I remember that ddb only sets %dr on the CPU it happens to execute.
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