On Fri, Apr 26, 2024 at 01:01:10PM -0700, Charlie Jenkins wrote:
On Fri, Apr 26, 2024 at 05:19:59PM +0100, Conor Dooley wrote:
On Sat, Apr 20, 2024 at 06:04:40PM -0700, Charlie Jenkins wrote:
@@ -163,6 +164,8 @@ void thead_errata_patch_func(struct alt_entry *begin, struct alt_entry *end, for (alt = begin; alt < end; alt++) { if (alt->vendor_id != THEAD_VENDOR_ID) continue;
if (alt->patch_id >= RISCV_VENDOR_EXT_ALTERNATIVES_BASE)continue;if (alt->patch_id >= ERRATA_THEAD_NUMBER)This number is 2, how does the patching actually work for vendor stuff when the base is always greater than 2?
Patching is handled through the patcher at the end of cpufeature.c. The vendor_id field is set in the alternatives for errata and now also for vendor extensions. The vendor extension patching is all handled generically.
This is distinguished by the patch_id being greater than RISCV_VENDOR_EXT_ALTERNATIVES_BASE, which should leave way more than enough room for errata ids. Since the code already checks if the patch_id is greater than the errata number, I can drop the "if (alt->patch_id >= RISCV_VENDOR_EXT_ALTERNATIVES_BASE)" check.
Ah, ye, I was being dumb - I was somehow thinking that you were using the errata patch function to patch this, which obviously wouldn't be a good design. If that had been the case, you'd never patch anything, but you patch the extensions using the cpufeature patch function so it all works out.
If anything, I guess there could be an assert here somewhere that enforces ERRATA_VENDOR_NUMBER < VENDOR_EXT_BASE.