Debug registers on FreeBSD‏

Julian Elischer julian at
Thu Feb 18 19:24:23 UTC 2010

Anderson Eduardo wrote:
> I want some papers, documentations or articles about Debug Registers on FreeBSD, I googled and didn't find any references about it. I'm using i386 AMD.
> Can someone help me?

Usually one does not use the debug registers directlym but instead 
uses one of the drivers that controls them.

for example the pmcstat program gives you access to the process 
accounting registers and control 'virtual' counters per process.

gdb (via the kernel) and other debug tools use various registers, so 
you want to make sure you are not interfering with them either.

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