here is take two. after booting in QEMU, i discovered this rediculous
isa string:

	rv64imafdch_zic64b_zicbom_zicbop_zicboz_ziccamoa_ziccif_zicclsm_ziccrse_zicntr_zicsr_zifencei_zihintntl_zihintpause_zihpm_zmmul_za64rs_zaamo_zalrsc_zawrs_zfa_zca_zcd_zba_zbb_zbc_zbs_shcounterenw_shgatpa_shtvala_shvsatpa_shvstvala_shvstvecd_ssccptr_sscounterenw_sstc_sstvala_sstvecd_ssu64xl_svadu_svvptc

without this change, the kernel will just print mojibake, and hangs when
booting secondary cores when the isa string overflows the buffer.

i have swapped to using sizeof to terminate the buffer, instead of
trusting OF_getprop's return value.
---
 sys/arch/riscv64/riscv64/cpu.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/sys/arch/riscv64/riscv64/cpu.c b/sys/arch/riscv64/riscv64/cpu.c
index e8400d4eed3..791ff2bfe15 100644
--- a/sys/arch/riscv64/riscv64/cpu.c
+++ b/sys/arch/riscv64/riscv64/cpu.c
@@ -73,7 +73,7 @@ const struct vendor {
 	{ 0, NULL }
 };
 
-char cpu_model[64];
+char cpu_model[512];
 int cpu_node;
 
 struct cpu_info *cpu_info_list = &cpu_info_primary;
@@ -102,7 +102,7 @@ size_t	thead_dcache_line_size;
 void
 cpu_identify(struct cpu_info *ci)
 {
-	char isa[32];
+	char isa[512];
 	uint64_t marchid, mimpid;
 	uint32_t mvendorid;
 	const char *vendor_name = NULL;
@@ -141,6 +141,7 @@ cpu_identify(struct cpu_info *ci)
 
 	len = OF_getprop(ci->ci_node, "riscv,isa", isa, sizeof(isa));
 	if (len != -1) {
+		isa[sizeof(isa) - 1] = 0;
 		printf(" %s", isa);
 		strlcpy(cpu_model, isa, sizeof(cpu_model));
 	}
-- 
2.49.0