On Mon, Nov 25, 2002 at 10:01:52AM -0000, atul srivastava wrote: > >The whole watch stuff in the the kernel is pretty much an ad-hoc > >API > >which I did create to debug a stack overflow. I'm sure if > >you're > >going to use it you'll find problems. For userspace for example > >you'd > >have to switch the watch register when switching the MMU context > >so > >each process gets it's own virtual watch register. > Beyond that there > >are at least two different formats of watch registers implemented > >in > >actual silicon, the original R4000-style and the MIPS32/MIPS64 > >style > >watch registers and the kernel's watch code only know the R4000 > >style (It's horrible what mailprograms accounts do to mail formatting ...) > my cpu manual ( IDT RC32334) talks about two watch registers > CP0_IWATCH and CP0_DWATCH where it is required to just put desired > VIRTUAL( bits 2--31) addresses to be watched , there is no mention > of CP0_WATCHLO and CP0_WATCHHI . > > additionally i guees for userspace virtual watch register problem, > the hardware takes care of all , i just need to specify my virual > address this is what i understand from my manual. > > and one more problem i face when i try to debug a mysterious page > fault problem, that i get my watch exception but after page fault > ..hence I can't really debug , shouldn't the priority of watch > exceptions should be higher than atleast instruction fetch > exception.? or the scope of debugging by watch exception is > limited by design..... No, the watch exception is one of the lowest priority exceptions. In case EXL/ERL are set it might even be defered making it the lowest priority exception. Ralf
