On 11/29/2014 01:41 AM, Duncan wrote:
Robert White posted on Sat, 29 Nov 2014 00:20:11 -0800 as excerpted:
l Display a summary of partition types. GPT uses a GUID to
identify partition types for particular OSes and purposes. For
ease of data entry, gdisk compresses these into two-byte
(four-digit hexadecimal) values that are related to their
equivalent MBR codes. Specifically, the MBR code is multiplied
by hexadecimal 0x0100.
That EFI uses GUIDs is one thing. That the standard allows these to be
selected based on type codes originally derived from ms-dos partition
type codes ("compressed" is the wrong word) is something else. If they
were "compressed" then it would be a relationship that could represent
any GUID at all. It's marginally hashed, in that there is a table
lookup, but its not properly a hashed as the "hash function" is
undefined for virtually all possible input values.
The other partition GUID is acutally more interesting.
So as I said, gdisk uses a 4-hexit short code based on the legacy MBR
type-code as an easy entry and display form referencing the longer and
much less human readable GUIDs, just like I said, and such usage is gdisk
specific, just like I said I thought it was.
Which is not what you said. None of the above was mentioned in the email
to which I responded.
What you actually said ::
[QUOTE]
Since I can't/won't run pretty much anything proprietary, there's little
chance of it being taken as anything but Linux, here. (Tho I actually
use (c)gdisk for partitioning here and it appears to use a different
GUID. (0700 in its short form which AFAIK is gdisk specific, for MS
basic data, while it uses 8300 for general Linux filesystems. I could
look up the long form GUIDs, but meh...)
[/QUOTE]
None of which is "gdisk specific", and all of which is based on EFI and
the GUID partition table.
What I mistakenly attributed to you and was key to my initial response
was your extension of Chris Murphy:
>>> Chris Murphy posted on Fri, 28 Nov 2014 00:10:40 -0700 as excerpted:
>>>> A very good example of WTF reusage of a UUID that irks me to no end is
>>>> GNU parted devs decided to recycle the Microsoft Windows Basic Data
>>>> partition type GUID for Linux partitions. It's like watching
someone get
>>>> run over by a zamboni with 50 feet of advance notice...
[So my bad there on the quoting...]
The irking there being dumb because the universally used "type GUID" has
nothing to do with the second GUID that universally identifies the
partition regardless of type.
But here is the thing... for all the screed about open and closed
source... (and I am an open source guy myself) The actual EFI standard
dictates these partition numbers and whatnot so if you used the
microsoft tools you'd get the same results.
http://en.wikipedia.org/wiki/GUID_Partition_Table#Partition_type_GUIDs
AND microsoft was one of several principle players in the EFI and its
GUID partition subparts.
So his being "irked to no end" and your agreement and "that's why I used
gdisk" response are both completely misplaced, and potentially
misleading to others.
I just went a little off the rails while trying to explain. /D'oh.
--
To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in
the body of a message to majord...@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
