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From: ludo@gnu.org (Ludovic =?utf-8?Q?Court=C3=A8s?=)
Subject: Re: GuixSD bootable ISO-9669 image
Date: Tue, 02 May 2017 23:11:05 +0200
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In-Reply-To: <20170502220904.3f27ce9f@scratchpost.org> (Danny Milosavljevic's
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To: Danny Milosavljevic <dannym@scratchpost.org>
Cc: guix-devel@gnu.org

Heya,

Danny Milosavljevic <dannym@scratchpost.org> skribis:

> On Tue, 02 May 2017 14:37:04 +0200
> ludo@gnu.org (Ludovic Court=C3=A8s) wrote:
>
>> Seems to work!
>
> Nice :)
>
>> Could you clarify the two =E2=80=9CSee grub=E2=80=9D in here:
>>=20
>> --8<---------------cut here---------------start------------->8---
>> (define (iso9660-superblock-uuid sblock)
>>   "Return the Volume ID of a iso9660 superblock SBLOCK as a 4-byte bytev=
ector."
>>   ;; Note: The field is the volume creation time.
>>   ;; FIXME Use only certain parts (See grub).
>>   ;; FIXME treat "all 0" as invalid.
>>   (sub-bytevector sblock 813 17))
>
> Yeah.  If you check out grub, /dev/disk/by-uuid or blkid, you can see tha=
t for ISO9660 filesystems, it prints the "uuids" differently (because they =
are not uuids, they are timestamps...).

OK.  Are these =E2=80=9CUUIDs=E2=80=9D 160-bit long like the =E2=80=9Creal=
=E2=80=9D ones?  If they are,
I=E2=80=99d suggest ignoring the problem for now.

>> Should =E2=80=98iso9660-uuid->string=E2=80=99 be different from =E2=80=
=98uuid->string=E2=80=99?
>
> From a purity standpoint I'd say no.  From a compatibility standpoint, ye=
s.

Makes sense.

>> Anyway, I think we should polish and commit real soon.  :-)  Perhaps we
>> can add a note about endianness and assume little endian for now.
>
> Turns out that for the parts that we need we don't care about the endiann=
ess either way.  So I dropped the endianness now.

Cool.

Thanks,
Ludo=E2=80=99.