On 19/03/21 15:06, Philippe Mathieu-Daudé wrote:
+ +/* Search RSDP signature. */ +static uintptr_t search_rsdp(uint32_t start_addr, uint32_t end_addr) +{ + uint64_t *rsdp_p; + + /* RSDP signature is always on a 16 byte boundary */ + for (rsdp_p = (uint64_t *)start_addr; rsdp_p < (uint64_t *)end_addr; + rsdp_p += 2) { + if (*rsdp_p == RSDP_SIGNATURE) { + return (uintptr_t)rsdp_p; + } + } + + return 0; +}gcc 10.2.1 "cc (Alpine 10.2.1_pre2) 10.2.1 20210313" reports:pc-bios/optionrom/pvh_main.c: In function 'search_rsdp': pc-bios/optionrom/pvh_main.c:61:21: warning: comparison is always false due to limited range of data type [-Wtype-limits] 61 | if (*rsdp_p == RSDP_SIGNATURE) { | ^~
This is probably a different bug, but I'll also add that uint64_t is supposed to be aligned to 64 bits, so you need either __attribute__((packed)), or use char* and memcmp. If you go for the latter, it would fix the issue that Philippe is reporting.
Paolo
