Update logs.

linux/pci.c

@@ -1,4 +1,6 @@
+#include <errno.h>
 #include <stdio.h>
+#include <string.h>
 #include <inttypes.h>
 #include <sys/types.h>
 #include <sys/stat.h>
@@ -16,8 +18,9 @@ __attribute__((stdcall)) uint32_t pci_read(uint32_t bus, uint32_t dev,
     uint32_t value = 0;
     sprintf(path, "%s/%4.4x:%2.2x:%2.2x.%u/config", pci_path, 0, bus, dev, fun);
     int fd = open(path, O_RDONLY);
-    if (!fd) {
-        // TODO: report an error
+    if (fd == -1) {
+//        fprintf(stderr, "[pci] error: failed to open config file '%s': %s\n",
+//                path, strerror(errno));
         return UINT32_MAX;
     }
     lseek(fd, offset, SEEK_SET);