On Tue, 24 Apr 2018 20:19:36 PDT (-0700), alankao@xxxxxxxxxxxxx wrote:
Hi Atish, Palmer, On Tue, Apr 24, 2018 at 06:15:49PM -0700, Atish Patra wrote:On 4/24/18 5:29 PM, Palmer Dabbelt wrote: >On Tue, 24 Apr 2018 15:16:16 PDT (-0700), atish.patra@xxxxxxx wrote: >>On 4/24/18 12:44 PM, Palmer Dabbelt wrote: >>>On Tue, 24 Apr 2018 12:27:26 PDT (-0700), atish.patra@xxxxxxx wrote: >>>>On 4/24/18 11:07 AM, Atish Patra wrote: >>>>>On 4/19/18 4:28 PM, Alan Kao wrote: >>>>>However, I got an rcu-stall for the test "47: Event times". >>>>># ./perf test -v 47 >>>>Got it working. The test tries to attach the event to CPU0 which doesn't >>>>exist in HighFive Unleashed. Changing it to cpu1 works. >>>> >>>>diff --git a/tools/perf/tests/event-times.c b/tools/perf/tests/event-times.c >>>>index 1a2686f..eb11632f 100644 >>>>--- a/tools/perf/tests/event-times.c >>>>+++ b/tools/perf/tests/event-times.c >>>>@@ -113,9 +113,9 @@ static int attach__cpu_disabled(struct perf_evlist >>>>*evlist) >>>> struct cpu_map *cpus; >>>> int err; >>>> >>>>- pr_debug("attaching to CPU 0 as enabled\n"); >>>>+ pr_debug("attaching to CPU 1 as disabled\n"); >>>> >>>>- cpus = cpu_map__new("0"); >>>>+ cpus = cpu_map__new("1"); >>>> if (cpus == NULL) { >>>> pr_debug("failed to call cpu_map__new\n"); >>>> return -1; >>>>@@ -142,9 +142,9 @@ static int attach__cpu_enabled(struct perf_evlist >>>>*evlist) >>>> struct cpu_map *cpus; >>>> int err; >>>> >>>>- pr_debug("attaching to CPU 0 as enabled\n"); >>>>+ pr_debug("attaching to CPU 1 as enabled\n"); >>>> >>>>- cpus = cpu_map__new("0"); >>>>+ cpus = cpu_map__new("1"); >>>> if (cpus == NULL) { >>>> pr_debug("failed to call cpu_map__new\n"); >>>> return -1; >>>> >>>> >>>>Palmer, >>>>Would it be better to officially document it somewhere that CPU0 doesn't >>>>exist in the HighFive Unleashed board ? >>>>I fear that there will be other standard tests/code path that may fail >>>>because of inherent assumption of cpu0 presence. >>> >>>I think the best way to fix this is to just have BBL (or whatever the >>>bootloader is) renumber the CPUs so they're contiguous and begin with 0. >> >>Do you mean BBL will update the device tree that kernel eventually parse >>and set the hart id? >>Sounds good to me unless it acts as a big hack in future boot loaders. > >Right now the machine-mode and supervisor-mode hart IDs are logically separate: >the bootloader just provides the hart ID as a register argument when starting >the kernel. Yes. BBL already needs to enumerate the harts by looking through the >device tree for various other reasons (at least to mask off the harts that >Linux doesn't support), so it's not that much effort to just maintain a mapping >from supervisor-mode hart IDs to machine-mode hart IDs. > But Linux also parses the device tree to get hart ID in riscv_of_processor_hart(). This is used to setup the possible/present cpu map in setup_smp(). Thus, Linux also need to see a device tree with cpu0-3 instead of cpu1-4. Otherwise, present cpu map will be incorrect. Isn't it ? >I have some patches floating around that do this, but appear to do it >incorrectly enough that nothing boots so maybe I'm missing something that makes >this complicated :). > Just a wild guess: May be the because of the above reason ;)Thanks for the test and discussion. It looks like am implementation issue from Unleash, so ... is there anything I should fix and provide a further patch?
You're welcome to fix BBL if you want, but that's unrelated to this patch set. I'm going to look over the code again as soon as I get a chance to, thanks for submitting the patches!
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