New versions of gcc report a potential error and there may be alignment
issues using uint64_t pointer to check the RSDP signature:
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) {
| ^~
Let's use memcmp() to get more readable code and avoid these issues.
Since pvh optionrom is baremetal, we use the compiler's __builtin_memcmp.
Reported-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Suggested-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Stefano Garzarella <sgarzare@redhat.com>
---
pc-bios/optionrom/pvh_main.c | 13 ++++++++-----
1 file changed, 8 insertions(+), 5 deletions(-)
diff --git a/pc-bios/optionrom/pvh_main.c b/pc-bios/optionrom/pvh_main.c
index 28e79d7fc4..12202e38c2 100644
--- a/pc-bios/optionrom/pvh_main.c
+++ b/pc-bios/optionrom/pvh_main.c
@@ -27,7 +27,8 @@ asm (".code32"); /* this code will be executed in protected
mode */
#include "optrom_fw_cfg.h"
#include "../../include/hw/xen/start_info.h"
-#define RSDP_SIGNATURE 0x2052545020445352LL /* "RSD PTR " */
+#define RSDP_SIGNATURE "RSD PTR "
+#define RSDP_SIGNATURE_SIZE 8
#define RSDP_AREA_ADDR 0x000E0000
#define RSDP_AREA_SIZE 0x00020000
#define EBDA_BASE_ADDR 0x0000040E
@@ -53,12 +54,14 @@ static uint8_t cmdline_buffer[CMDLINE_BUFSIZE];
/* Search RSDP signature. */
static uintptr_t search_rsdp(uint32_t start_addr, uint32_t end_addr)
{
- uint64_t *rsdp_p;
+ char rsdp_signature[RSDP_SIGNATURE_SIZE] = RSDP_SIGNATURE;