On 08/24/2012 02:13 AM, Lukasz Majewski wrote:
The restoration of GPT table (both primary and secondary) is now possible. Simple GUID generation is supported.
+/**
- guid_gen(): Generate UUID
- @param dev_desc - block device descriptor
- @return - generated UUID table
- NOTE: The entrophy of this function is small
- */
+static u8 *guid_gen(block_dev_desc_t * dev_desc) +{
- int k = 0;
- static int i = 1;
- static u8 __aligned(CONFIG_SYS_CACHELINE_SIZE) guid[16];
Hmmm. Wouldn't it be better to take a pointer to the GUID as a parameter rather than returning a pointer to the same static over and over again. That way, the caller won't cause problems if they call this function 4 times, and cache the pointer each time.
- static u8 __aligned(CONFIG_SYS_CACHELINE_SIZE) ent_pool[512];
- u32 *ptr = (u32 *) guid;
- /* Entrophy initialization - read random content of one SD sector */
- if (i == 1) {
debug("Init entropy:%x\n", (u32)(dev_desc->lba >> 14));if (dev_desc->block_read(dev_desc->dev, (dev_desc->lba >> 14),1, (u32 *) ent_pool) != 1) {
I imagine you might get more entropy out of just reading sector 0, or 1 (or both) than some random sector in the middle of the disk, which quite possibly won't ever have been written to.
Is there any particular reason why ">> 14" rather than any other shift?
printf("** Can't read from device %d **\n",dev_desc->dev);}- }
- for (k = 0; k < 4; k++) {
*(ptr + k) = efi_crc32((const void *) ent_pool,sizeof(ent_pool));ent_pool[511 - k] = *(ptr + k);- }
- ent_pool[0] = ((u8) i) & 0xff;
That doesn't quite implement a fully compliant UUID. According to:
http://en.wikipedia.org/wiki/Universally_unique_identifier
the "variant" (UUID) and "version" (4; random) should be encoded into a few specific bits of the final UUID value.
- debug("GUID: ");
- for (k = 0; k < sizeof(guid); k++)
debug(" %x ", guid[k]);
I think inventing (stealing from Linux) a proper UUID formatting function would be useful; that way it could be shared by print_part_efi() if that function was ever enhanced to print the partition UUID and partition type UUID.
- debug(" i:%d,\n", i);
- i++;
- return guid;
+}