automount doesn't work without GPT table

[Alexander Shiyan <eagle.alexander923@gmail.com>]

Hello All.

I found that automounting does not work without a GPT table.
In the example below, it is not possible to automatically mount a
partition from an MMC card.
However, if I add the full paths to the command manually, everything works.

barebox 2025.02.0-00690-ga6a0a0ba4f61 #12 Thu Feb 27 08:27:56 MSK 2025
Board: Mega-Milas MM-SM-SAMA5D2
AT91: Detected soc type: sama5d2
AT91: Detected soc subtype: sama5d27c_d1g
...
sdhci-at91 b0000000.sdio-host@b0000000.of: registered as mmc1
mmc1: detected SD card version 2.0
mmc1: registered mmc1
...
barebox@Mega-Milas Informer SAMA5D2:/ ls /mnt/mmc1.0
mount: Device or resource busy
running automount command 'mount mmc1.0' failed
ls: No such device

barebox@Mega-Milas Informer SAMA5D2:/ automount -l
/mnt/mmc1            mount mmc1
/mnt/mmc1.0          mount mmc1.0
/mnt/mmc1.1          mount mmc1.1
/mnt/tftp            ifup -a1 && mount -t tftp $global.net.server /mnt/tftp
/mnt/nfs             ifup -a1 && mount -t nfs
${global.net.server}:/home/${global.user}/nfsroot/${global.hostname}
/mnt/nfs
/mnt/ratp            mount -t ratpfs none /mnt/ratp

barebox@Mega-Milas Informer SAMA5D2:/ automount /mnt/mmc1.0  "mount
/dev/mmc1.0 /mnt/mmc1.0"
barebox@Mega-Milas Informer SAMA5D2:/ ls /mnt/mmc1.0
BOOT.BIN           barebox.bin        barebox.env        rootfs.squashfs

With the GPT table on the MMC, everything works OK out of the box:

sdhci-at91 b0000000.sdio-host@b0000000.of: registered as mmc1
mmc1: detected SD card version 2.0
WARNING: mmc1: GPT:Primary header thinks Alt. header is not at the end
of the disk.
WARNING: mmc1: GPT:395303 != 60440575
WARNING: mmc1: GPT:Alternate GPT header not at the end of the disk.
WARNING: mmc1: GPT:395303 != 60440575
WARNING: mmc1: GPT: Use parted to correct GPT errors.
mmc1: registered mmc1
...

barebox@Mega-Milas Informer SAMA5D2:/ ls /mnt/mmc1.0
mounted /dev/mmc1.0 on /mnt/mmc1.0
BOOT.BIN           barebox.bin        barebox.env        rootfs.squashfs