Em Mon, Jan 26, 2015 at 12:16:21PM +0000, Will Deacon escreveu: > On Mon, Jan 26, 2015 at 12:12:43PM +0000, Arnaldo Carvalho de Melo wrote: > > Em Mon, Jan 26, 2015 at 10:27:11AM +0000, Will Deacon escreveu: > > > On Sun, Jan 25, 2015 at 03:56:52PM +0000, Russell King - ARM Linux wrote: > > > > On Sat, Jan 24, 2015 at 04:23:42PM -0600, Felipe Balbi wrote: > > > > > yeah, I'll try a few older kernels, also see if I can reproduce on other > > > > > boards. > > > > > > > > Perf works for me with CONFIG_FRAME_POINTER=y, but that's only for kernel > > > > space, and for userspace where the programs have been built for ARM mode > > > > with frame pointers. > > > > > > > > The kernel may work without CONFIG_FRAME_POINTER set, but I've never > > > > tested that, and I'd suggest that (given my experience looking at oops > > > > dumps) it's not all that reliable. > > > > > > > > Lastly, userspace without frame pointers is pretty much hopeless. > > > > > > FWIW, perf can now use libunwind for unwinding the userspace side of > > > things, so it's not quite as bad as it used to be. For the kernel side, > > > if the unwinder isn't working properly it would be nice to know *why*, > > > but I agree that it tends to be far flakier than the frame-pointer method. > > > > Any idea why, with userspace using frame pointers, perf doesn't go all > > the way from kernel to userspace main() (or whatever is the endpoint), > > as Russel stated? > > Did he state that? I thought he was just saying that he couldn't unwind > userspace when *not* using frame pointers, which requires you to link sorry, yeah I misunderstood, so all is good for kernel + userspace when both are built with frame pointers :-) "The only for kernel space" caught my attention, I thought that he said that it works only for the kernel with frame pointers, even with a userspace built with fp. - Arnaldo > a recent perf with a bleeding-edge libunwind. > > Will -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
