On 03/26/2014 06:00 AM, Przemyslaw Marczak wrote: > On 03/25/2014 08:28 PM, Stephen Warren wrote: >> On 03/19/2014 11:58 AM, Przemyslaw Marczak wrote: >>> This patch adds support to generate UUID (Universally Unique Identifier) >>> in version 4 based on RFC4122, which is randomly. >>> >>> Source: https://www.ietf.org/rfc/rfc4122.txt
>>> diff --git a/lib/uuid.c b/lib/uuid.c >> >>> /* >>> * UUID - Universally Unique IDentifier - 128 bits unique number. >>> * There are 5 versions and one variant of UUID defined by RFC4122 >>> - * specification. Depends on version uuid number base on a time, >>> - * host name, MAC address or random data. >>> + * specification. Depends on version uuid number base on: >> >> I still have no idea what "Depends on version uuid number base on" means. > > It means that each UUID version "result" depends on different source > data, as listed here... How bout replacing that sentence with: A UUID contains a set of fields. The set varies depending on the version of the UUID, as shown below: >>> + * - time, MAC address(v1), >>> + * - user ID(v2), >>> + * - MD5 of name or URL(v3), >>> + * - random data(v4), >>> + * - SHA-1 of name or URL(v5), >>> + * timestamp - 60-bit: time_low, time_mid, time_hi_and_version >>> + * version - 4 bit (bit 4 through 7 of the time_hi_and_version) >>> + * clock seq - 14 bit: clock_seq_hi_and_reserved, clock_seq_low >>> + * variant: - bit 6 and 7 of clock_seq_hi_and_reserved >>> + * node - 48 bit >>> + * In this version all fields beside 4 bit version are randomly generated. >>> + * source: https://www.ietf.org/rfc/rfc4122.txt >> >> gen_rand_uuid() doesn't actually honor that format; it creates pure >> random data rather than filling in any timestamps, clock sequence >> data, etc. > > Actually, yes but two fields are NOT set randomly, and this is what > comment includes: > "In this version all fields beside 4 bit version are randomly generated." > Moreover the gen_rand_uuid() respects endianess for setting bits, > and this could be checked on linux host by "uuid -d uboot_uuid_string" > in shell. While it's true that some fields are set non-randomly, most aren't; you really can't claim that e.g. placing random data in the timestamp field is a valid timestamp. _______________________________________________ U-Boot mailing list U-Boot@lists.denx.de http://lists.denx.de/mailman/listinfo/u-boot
