[Crash-utility] Re: [RFC PATCH 1/2] add cpu_to_nid function

On Tue, Aug 04, 2026 at 06:35:20PM +1200, Tao Liu wrote: > Hi Huang, > > On Mon, Jul 20, 2026 at 8:52 PM Huang Shijie <huangsj(a)hygon.cn&gt; wrote: > > > > Add cpu_to_nid function which we can use to get the NUMA node id > > by the cpu id. > > > > Signed-off-by: Huang Shijie <huangsj(a)hygon.cn&gt; > > --- > > defs.h | 2 ++ > > kernel.c | 46 ++++++++++++++++++++++++++++++++++++++++++++++ > > main.c | 1 + > > 3 files changed, 49 insertions(+) > > > > diff --git a/defs.h b/defs.h > > index a4f70b7..98a149b 100644 > > --- a/defs.h > > +++ b/defs.h > > @@ -6040,6 +6040,8 @@ ulong do_maple_tree(ulong, int, struct list_pair *); > > void help_init(void); > > void cmd_usage(char *, int); > > void display_version(void); > > +int cpu_to_nid(int cpu); > > +void numa_init(void); > > void display_help_screen(char *); > > #ifdef ARM > > #define dump_machdep_table(X) arm_dump_machdep_table(X) > > diff --git a/kernel.c b/kernel.c > > index eb9754c..15254a4 100644 > > --- a/kernel.c > > +++ b/kernel.c > > @@ -12207,3 +12207,49 @@ out: > > pc->error_fp = error_fp_save; > > } > > #endif > > + > > +static int *cpu_to_nid_map; > > + > > +int > > +cpu_to_nid(int cpu) > > +{ > > + if (!cpu_to_nid_map || cpu < 0 || cpu >= kt->cpus) > > + return -1; > > + if (vt->numnodes == 1) > > + return 0; > > + return cpu_to_nid_map[cpu]; > > +} > > + > > +static void > > +cpu_to_nid_init(void) > > +{ > > + int i, j; > > + int fd; > > + char buf[64]; > > + > > + cpu_to_nid_map = malloc(kt->cpus * sizeof(int)); > > + if (vt->numnodes == 1) > > + return; > > + > > + memset(cpu_to_nid_map, -1, kt->cpus * sizeof(int)); > > + > > + for (i = 0; i < kt->cpus; i++) { > > + for (j = 0; j < vt->numnodes; j++) { > > + memset(buf, 0, sizeof(buf)); > > + sprintf(buf, "/sys/devices/system/cpu/cpu%d/node%d", i, j); > > This will only work for live debug, rather than vmcore debug, won't > it? If so, I suggest supporting vmcore debug as well, so we can remove > the "/sys" dir reading. > okay. I will wwitch to read the kernel symbol to get the cpu_to_node info. (For x86_64, we can read the "x86_cpu_to_node_map".)

Thanks Huang Shijie