Messages in this thread | | | Date | Tue, 10 Mar 2009 15:50:36 +0100 | From | Ingo Molnar <> | Subject | Re: [patch 01/11] Introducing generic hardware breakpoint handler interfaces |
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* Alan Stern <stern@rowland.harvard.edu> wrote:
> On Tue, 10 Mar 2009, Ingo Molnar wrote: > > > * prasad@linux.vnet.ibm.com <prasad@linux.vnet.ibm.com> wrote: > > > > > > > +static u8 tprio[HB_NUM]; /* Thread bp max priorities */ > > > +LIST_HEAD(kernel_bps); /* Kernel breakpoint list */ > > > +static LIST_HEAD(thread_list); /* thread_hw_breakpoint list */ > > > +DEFINE_PER_CPU(struct cpu_hw_breakpoint, cpu_bp); > > If nobody minds, I'll answer some of these questions on > Prasad's behalf because they address parts of the code that > were written before he took over the project. > > > hm, why do we need the whole 'priority' mechanism? It seems > > very over-designed to me. > > This was done at Roland McGrath's express request. We should > see what he has to say about it. > > > The likelyhood of both user-space and kernel-space to use > > hw-breakpoints is very low to begin with. And if they use > > them, the likelyhood of there being more than 4 debugregs > > required in the same context is even lower. > > Not all architectures have 4 debug registers. Most have only > one. > > > If that happens we shouldnt try to be too smart about them - > > just override user-space ones with kernel space ones and > > that's it. No explicit priorities are needed. > > Roland really did not want it done this way.
Well i guess i'll have to wait for Roland's reply then.
Ingo
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