Other When/what generates /dev/msdosfs/*?

dl8dtl · Feb 24, 2023

As mentioned in another thread, I just migrated my arm64 machine (RockPi4) from SD-Card to NVMe SSD.
The original SD-card system mounts the EFI boot partition from /dev/msdosfs/EFI, where "EFI" is the label used inside the msdsofs.
When booting from the NVMe SSD, this failed because this verbatim copy of the same FAT filesystem no longer generates an entry under /dev/msdosfs. Changing /etc/fstab to use the /dev/diskid/${id} entry works, the copied filesystem is fully operable.
So the question is (see subject): when/what generates these /dev/msdosfs entries?

Alain De Vos · Feb 24, 2023

"Verbatim copy", does that include boot-record, partition-table, all slices and all partitions ?
Perform

Code:

gpart show -p
gpart show -l

This on the SD-Card & On the NVME-SSD to check for differences between the two.

Phishfry · Feb 25, 2023

dl8dtl said:
what generates these /dev/msdosfs entries?

msdosfs Disk Labels I believe.

/boot/loader.conf to disable msdosfs labels
#kern.geom.label.msdosfs.enable=1

I usually disable that fstab setting for the EFI partition.
Unless modifying EFI it does not need not be mounted at all.

Phishfry · Feb 25, 2023

glabel(8) to be exact...

MSDOSFS (FAT12, FAT16, FAT32) (directory /dev/msdosfs/)

Phishfry · Feb 25, 2023

I really cringe when I see the example in that manpage.
glabel label -v usr /dev/da2

We have not used the old style disk names since 2009-2011.

ada(4)

man.freebsd.org

Having good documentation makes FreeBSD enjoyable.
Keeping it fresh should be considered.
I believe we should have a lower bar for documentation refresh.

We had some guy that was helping and now he is only being reddit moderator.
i dont know what happened to him.

I shouldn't have to fill out a PR to update the docs.
Examples are really meaningful in difficultly worded technical documentation.

dl8dtl · Feb 25, 2023

Phishfry said:
I really cringe when I see the example in that manpage.
glabel label -v usr /dev/da2

We have not used the old style disk names since 2009-2011.

ada(4)

man.freebsd.org

Having good documentation makes FreeBSD enjoyable.
Keeping it fresh should be considered.
I believe we should have a lower bar for documentation refresh.

We had some guy that was helping and now he is only being reddit moderator.
i dont know what happened to him.

I shouldn't have to fill out a PR to update the docs.
Examples are really meaningful in difficultly worded technical documentation.

Well, /dev/da* are still there, depending on your device – e.g. on USB storage devices.
But OK, you typically no longer have a "usr" label on those.

dl8dtl · Feb 25, 2023

Alain De Vos said:
"Verbatim copy", does that include boot-record, partition-table, all slices and all partitions ?
Perform

Code:

gpart show -p gpart show -l

This on the SD-Card & On the NVME-SSD to check for differences between the two.

Yes, "verbatim copy" means the copy was initially a full dd from the card to the SSD. Afterwards, I fixed the GPT (2nd copy was not at end of medium), and eventually removed the large UFS and swap partitions, to replace them by a partition for a ZFS pool. However, the first (EFI) partition was not touched anymore.

Code:

root@generic:~ # gpart show -p
=>       40  488397088    diskid/DISK-Z0HA32PEK2L2  GPT  (233G)
         40      32728                              - free -  (16M)
      32768     102400  diskid/DISK-Z0HA32PEK2L2p1  efi  (50M)
     135168  488261960  diskid/DISK-Z0HA32PEK2L2p2  freebsd-zfs  (233G)

root@generic:~ # gpart show -l
=>       40  488397088  diskid/DISK-Z0HA32PEK2L2  GPT  (233G)
         40      32728                            - free -  (16M)
      32768     102400                         1  efi  (50M)
     135168  488261960                         2  ZROOT  (233G)

I can certainly live with explicitly mention the disk ID in /etc/fstab, I was merely curious about why one setup created that entry and the other one doesn't.
The respective entries from the SD card are (inserted in a different computer, it's no longer mounted in the RockPi):

Code:

root@uriah:~ # gpart show -l
=>      40  62333872  da0  GPT  (30G)
        40     32728       - free -  (16M)
     32768    102400    1  efi  (50M)
    135168  55824384    2  rootfs  (27G)
  55959552   6373376    3  (null)  (3.0G)
  62332928       984       - free -  (492K)

=>      40  62333872  diskid/DISK-20120501030900000  GPT  (30G)
        40     32728                                 - free -  (16M)
     32768    102400                              1  efi  (50M)
    135168  55824384                              2  rootfs  (27G)
  55959552   6373376                              3  (null)  (3.0G)
  62332928       984                                 - free -  (492K)
root@uriah:~ # gpart show -p
=>      40  62333872    da0  GPT  (30G)
        40     32728         - free -  (16M)
     32768    102400  da0p1  efi  (50M)
    135168  55824384  da0p2  freebsd-ufs  (27G)
  55959552   6373376  da0p3  freebsd-swap  (3.0G)
  62332928       984         - free -  (492K)

=>      40  62333872    diskid/DISK-20120501030900000  GPT  (30G)
        40     32728                                   - free -  (16M)
     32768    102400  diskid/DISK-20120501030900000p1  efi  (50M)
    135168  55824384  diskid/DISK-20120501030900000p2  freebsd-ufs  (27G)
  55959552   6373376  diskid/DISK-20120501030900000p3  freebsd-swap  (3.0G)
  62332928       984                                   - free -  (492K)

(Hihi, with those "da0" entries again. ;-)

dl8dtl · Feb 25, 2023

Phishfry said:
msdosfs Disk Labels I believe.

/boot/loader.conf to disable msdosfs labels
#kern.geom.label.msdosfs.enable=1

I usually disable that fstab setting for the EFI partition.
Unless modifying EFI it does not need not be mounted at all.

Code:

root@generic:~ # sysctl kern.geom.label
kern.geom.label.disk_ident.enable: 1
kern.geom.label.gptid.enable: 1
kern.geom.label.gpt.enable: 1
kern.geom.label.ufs.enable: 1
kern.geom.label.ufsid.enable: 1
kern.geom.label.reiserfs.enable: 1
kern.geom.label.ntfs.enable: 1
kern.geom.label.msdosfs.enable: 1
kern.geom.label.iso9660.enable: 1
kern.geom.label.flashmap.enable: 1
kern.geom.label.ext2fs.enable: 1
kern.geom.label.debug: 0

yuripv79 · Feb 25, 2023

dl8dtl said:
Well, /dev/da* are still there, depending on your device – e.g. on USB storage devices.

Yep, as well as widely used SAS disks, so there's nothing wrong with "da" names.

Phishfry said:
I really cringe when I see the example in that manpage.

You must be confusing it with "ad" names?

Phishfry · Feb 25, 2023

yuripv79 said:
You must be confusing it with "ad" names?

Yup lack of sleep. Lots of overtime...

Alain De Vos · Feb 25, 2023

Phishfry on personal level. Sleep is very important.
U.S. Army did experiments with sleep deprivation...