Merge pull request #5914 from martin-frbg/u74detect

Add cpu detection for Sifive U74

Author: martin-frbg

cpuid_riscv64.c

@@ -98,9 +98,10 @@ static char *cpuname_lower[] = {
 int detect(void){
 #ifdef __linux
   FILE *infile;
-  char buffer[512],isa_buffer[512],model_buffer[512];
+  char buffer[512],isa_buffer[512],model_buffer[512], uarch_buffer[512];
   const char* check_c910_str = "T-HEAD C910";
-  char *pmodel = NULL, *pisa = NULL;
+  const char* check_u74_str = "sifive,u74";
+  char *pmodel = NULL, *pisa = NULL, *puarch = NULL;
 
   infile = fopen("/proc/cpuinfo", "r");
   if (!infile)
@@ -113,6 +114,13 @@ int detect(void){
         pmodel++;
     }
 
+    if(!strncmp(buffer, "uarch", 5)){
+      strcpy(uarch_buffer, buffer);
+      puarch = strchr(uarch_buffer, ':');
+      if (puarch)
+        puarch++;
+    }
+
     if(!strncmp(buffer, "isa", 3)){
       strcpy(isa_buffer, buffer);
       pisa = strchr(isa_buffer, '4');
@@ -123,12 +131,16 @@ int detect(void){
 
   fclose(infile);
 
-  if (!pmodel || !pisa)
+  if ((!pmodel && !puarch) || !pisa)
    return(CPU_GENERIC);
 
-  if (strstr(pmodel, check_c910_str) && strchr(pisa, 'v'))
-    return CPU_C910V;
-
+  if (pmodel) {
+    if (strstr(pmodel, check_c910_str) && strchr(pisa, 'v'))
+      return CPU_C910V;
+  } else if (puarch) {
+    if (strstr(puarch, check_u74_str) && !strchr(pisa, 'v'))
+      return CPU_U74;
+  }
   return CPU_GENERIC;
 #endif