Messages in this thread | | | Date | Thu, 25 Apr 2013 17:10:35 +0200 | From | Oleg Nesterov <> | Subject | Re: [PATCH V2 1/4] perf: Add hardware breakpoint address mask |
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On 04/25, Frederic Weisbecker wrote: > > 2013/4/23 Jacob Shin <jacob.shin@amd.com>: > > @@ -286,7 +286,10 @@ struct perf_event_attr { > > __u64 config1; /* extension of config */ > > }; > > union { > > - __u64 bp_len; > > + struct { > > + __u32 bp_len; > > + __u32 bp_addr_mask; > > + }; > > Do we need len and mask to work at the same time? I can't think of a > situation when len and mask mix up together in a useful way to define > a range.
And it would be nice (I think) if we could simply turn bp_len into bp_mask. It is already the mask actually, bp_addr should be aligned.
But I do not see how we can do this, so I guess we need another field.
Well. Another option is to extend bp_len. Fortunately HW_BREAKPOINT_LEN_* match the length, so we can simply allow any 2^n length and amd.c can translate it into the mask.
Of course, this doesn't allow to use, say, mask=0xF0. But perhaps this is not really useful?
I dunno. I leave this to you and Jacob ;)
Oleg.
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