On Thu, Dec 10, 2009 at 08:24:36PM +0100, Oleg Nesterov wrote: > On 12/09, CAI Qian wrote: > > > > ----- "Oleg Nesterov" <o...@redhat.com> wrote: > > > > > Thanks, but it doesn't fail for me on this machine... > > > > Hmm, it failed for me. > > > > # cd /root/ptrace-tests > > > > # make check > > ... > > FAIL: watchpoint > > OMG. Yet another test-case fails on powerpc ???? I didn't see this > failure in the previous reports or missed it ... > > I bet it fails without utrace too? (please don't tell it doesn't ;) > > Did you see it fails on other ppc64 machines? > > > Oh well. I spent this day grepping arch/powerpc to understand how > PTRACE_SET_DEBUGREG works and what is the problem. But I am afraid > this time I need a help from someone who understands the hardware > magic on powerpc. >
There's relatively less magic with PPC64 (with just one DABR) compared to x86 :-) I hope to offer a little help here (given that I work to tweak ptrace_set_debugreg() in PPC64 to use the hw-breakpoint interfaces).... Watchpoints (using DABR) through GDB can fail for many reasons....they must ideally be set after the program has started execution - to enable GDB know the size of the variable...else they would resort to single-stepping to trap access to the target variable. Cai, Where can one find the relevant piece of testcase? Thanks, K.Prasad