On Mon, 2010-03-29 at 17:01 +0530, K.Prasad wrote: > On Fri, Mar 26, 2010 at 04:11:45PM -0500, Dave Kleikamp wrote: > > On Tue, 2010-03-23 at 19:37 +0530, K.Prasad wrote: > > > plain text document attachment (ppc64_hbkpt_02) > > > Implement perf-events based hw-breakpoint interfaces for PPC64 processors. > > > These interfaces help arbitrate requests from various users and schedules > > > them as appropriate. > > > > > > Signed-off-by: K.Prasad <pra...@linux.vnet.ibm.com> > > > > SNIP > > > > > Index: linux-2.6.ppc64_test/arch/powerpc/include/asm/cputable.h > > > =================================================================== > > > --- linux-2.6.ppc64_test.orig/arch/powerpc/include/asm/cputable.h > > > +++ linux-2.6.ppc64_test/arch/powerpc/include/asm/cputable.h > > > @@ -511,6 +511,13 @@ static inline int cpu_has_feature(unsign > > > & feature); > > > } > > > > > > +#define CPU_FTR_HAS_DABR (defined(CONFIG_PPC64) && \ > > > + !defined(CONFIG_PPC_ADV_DEBUG_REGS)) > > > +#ifdef CPU_FTR_HAS_DABR > > > +/* Number of physical HW breakpoint registers */ > > > +#define HBP_NUM 1 > > > +#endif > > > + > > > #endif /* !__ASSEMBLY__ */ > > > > > > #endif /* __KERNEL__ */ > > > > These new defines don't really correlate to the cpu table. One would > > expect cpu_has_feature(CPU_FTR_HAS_DABR) to have meaning, but it would > > have to be defined similar to the other CPU_FTR_ constants, and or-ed > > with CPU_FTRS_ALWAYS (when appropriate). > > > > The code can be changed as below: > > #if (defined(CONFIG_PPC64) && !defined(CONFIG_PPC_ADV_DEBUG_REGS)) > #define CPU_FTR_HAS_DABR 1 > /* Number of physical HW breakpoint registers */ > #define HBP_NUM 1 > #endif > > However, a config option CONFIG_PPC_BOOK3S_64 (I just found) whose scope > includes only 64-bit server processors (having one DABR) to be the most > suitable. > > I think it must be used in lieu of introducing a new CPU_FTR_HAS_DABR > definition in cputable.h > > > > Similarly, I would expect the cpu_spec structure to have a new field, > > hbp_num, which is initialized in cputable.c. Maybe a longer name would > > be better, num_hw_brkpts? > > > > There are a few issues with such an approach: > i) Two such fields would be required in 'struct cpu_spec' - one for > instruction breakpoints and other for data. > ii) As pointed out by you below, hbp_num or num_hw_brkpts would always > be assigned to the compile time constant HBP_NUM (hence a variable is not > required to store it). > iii) HBP_NUM still cannot be entirely removed as it is used by generic > kernel/hw_breakpoint.c code (and is used by x86 code as well). > > I think the simplest approach would be to have the following entry in > cputable.h (and get away with the rest of the additions seen in patch > ver XV) > > #ifdef CONFIG_PPC_BOOK3S_64 > #define HBP_NUM 1 > #endif > > The next version of the patch should contain changes to that effect > (assuming I hear no objections).
I just don't think this belongs in cputable.h. Why not put this in hw_breakpoint.h? -- David Kleikamp IBM Linux Technology Center _______________________________________________ Linuxppc-dev mailing list Linuxppc-dev@lists.ozlabs.org https://lists.ozlabs.org/listinfo/linuxppc-dev
