Subject: ptrace (was: Re: gdb breakpoint setting with UVM)
To: None <tech-kern@netbsd.org>
From: Chuck Cranor <chuck@research.att.com>
List: tech-kern
Date: 02/16/1999 21:54:02
>looking at PR 6152 by Michael Hitch, I expect that it is a problem for _any_
>machine using in-memory breakpoint instructions with seperate I/D-cache...

>- did anybody else notice the problem?
>- how does gdb insert breakpoints on our different architectures?


as i understand it the problem comes about when you've got a seperate
I and D cache.   in that case you need to flush the i-cache properly
when ptrace is used.

the ptrace man page has a PT_WRITE_I and PT_READ_I directive, but
internally the kernel treats these two exactly the same (which seems
wrong to me).  

i had the impression that there should be some sort MD hook to flush
the I-cache in the PT_WRITE_I case?


chuck