Date: Sun, 10 Jul 2022 16:26:02 -0300 From: "Dr. Rolf Jansen" <freebsd-rj@cyclaero.com> To: freebsd-arm <freebsd-arm@freebsd.org> Subject: Partition layout of ARM SD card images Message-ID: <1F42EED0-B39F-4E33-986A-FB70A3AA4362@cyclaero.com>
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For example let's have a llok on the partition layout of, =
FreeBSD-13.1-RELEASE-arm64-aarch64-RPI.img (the others are similar):
# mdconfig -a -u 0 -t vnode -f =
diskimg/FreeBSD-13.1-RELEASE-arm64-aarch64-RPI.img
# gpart show md0 md0s2
=3D> 63 6291393 md0 MBR (3.0G)
63 2016 - free - (1.0M)
2079 102312 1 fat32lba [active] (50M)
104391 6187041 2 freebsd (3.0G)
6291432 24 - free - (12K)
=3D> 0 6187041 md0s2 BSD (3.0G)
0 57 - free - (29K)
57 6186880 1 freebsd-ufs (2.9G)
6186937 104 - free - (52K)
The start of the fat32 boot slice s1 (containing the u-boot) stuff is =
neither aligned to 1M nor to 4k, it starts on an odd base. The start of =
the BSD payload slice s2 and its size are odd as well. The padding of 57 =
blocks within s2 lets the UFS partition start on a globally even base, =
namely 104391+57 =3D 104448, which as a matter of fact is 4k aligned =
(104448*512/4096 =3D 13056) and 1M aligned as well (104448*512/1024/1024 =
=3D 51), however all this keeps looking strange.
Are there reasons for this partition layout besides making it look more =
interesting? If yes, some insights would be good.
For the time being, I created a second SD card from the initial one for =
my RPi 4, and it's partition table is as follows:
=20
# gpart show mmcsd0 mmcsd0s2
=3D> 63 62410689 mmcsd0 MBR (30G)
63 25 - free - (13K)
88 102312 1 fat32lba [active] (50M)
102400 62308352 2 freebsd (30G)
=3D> 0 62308352 mmcsd0s2 BSD (30G)
0 56623104 1 freebsd-ufs (27G)
56623104 5685248 2 freebsd-swap (2.7G)
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