riscv: print hartid on bringup

Firmware randomly releases cores, so CPU numbers don't linearly map
to hartids. When the system has an exception, we care more about hartids.
Adding "dyndbg="file smpboot.c +p" loglevel=8" to the cmdline can output
the hartid.

Signed-off-by: Yunhui Cui <cuiyunhui@bytedance.com>
Reviewed-by: Alexandre Ghiti <alexghiti@rivosinc.com>
Link: https://lore.kernel.org/r/20250303083424.14309-1-cuiyunhui@bytedance.com
Signed-off-by: Alexandre Ghiti <alexghiti@rivosinc.com>

diff --git a/arch/riscv/kernel/smp.c b/arch/riscv/kernel/smp.c
index d58b5e7..e650dec 100644 (file)
--- a/arch/riscv/kernel/smp.c
+++ b/arch/riscv/kernel/smp.c
@@ -48,6 +48,8 @@ EXPORT_SYMBOL_GPL(__cpuid_to_hartid_map);
 void __init smp_setup_processor_id(void)
 {
        cpuid_to_hartid_map(0) = boot_cpu_hartid;
+
+       pr_info("Booting Linux on hartid %lu\n", boot_cpu_hartid);
 }
 
 static DEFINE_PER_CPU_READ_MOSTLY(int, ipi_dummy_dev);

diff --git a/arch/riscv/kernel/smpboot.c b/arch/riscv/kernel/smpboot.c
index e36d202..601a321 100644 (file)
--- a/arch/riscv/kernel/smpboot.c
+++ b/arch/riscv/kernel/smpboot.c
@@ -231,6 +231,10 @@ asmlinkage __visible void smp_callin(void)
        riscv_ipi_enable();
 
        numa_add_cpu(curr_cpuid);
+
+       pr_debug("CPU%u: Booted secondary hartid %lu\n", curr_cpuid,
+               cpuid_to_hartid_map(curr_cpuid));
+
        set_cpu_online(curr_cpuid, true);
 
        /*