[Letux-kernel] Subtle issue with U-Boot and kernel and SD card UUIDs

H. Nikolaus Schaller hns at goldelico.com
Tue May 23 16:41:56 CEST 2017


> Am 23.05.2017 um 16:17 schrieb H. Nikolaus Schaller <hns at goldelico.com>:
> 
> 
> Something like: https://johnkastler.net/2012/02/05/changing-disk-identifier-using-fdisk/

I now changed the disk identifier to some random value
and voilà, even blkid shows that as PARTUUID (it knows both UUID and PARTUID)

root at letux:~# blkid
/dev/mmcblk0p1: LABEL="boot" UUID="E052-71A6" TYPE="vfat"
/dev/mmcblk0p2: LABEL="rootfs" UUID="5db8fefe-f8d2-46e4-828a-ab4fe1b8f9b4" TYPE="ext3"
/dev/mmcblk1p1: LABEL="boot" UUID="7BFC-21B7" TYPE="vfat" PARTUUID="00bc614e-01"
/dev/mmcblk1p2: LABEL="rootfs" UUID="256560b9-884a-4f26-b910-e3735446c9bb" TYPE="ext3" PARTUUID="00bc614e-02"
/dev/mmcblk0: PTTYPE="dos"
/dev/mmcblk1: PTUUID="00bc614e" PTTYPE="dos"
root at letux:~# 

U-Boot:

=> part list mmc 0

Partition Map for MMC device 0  --   Partition Type: DOS

Part    Start Sector    Num Sectors     UUID            Type
  1     128             3116691         00bc614e-01     0c Boot
  2     3116819         59217133        00bc614e-02     83
=> part list mmc 1

Partition Map for MMC device 1  --   Partition Type: DOS

Part    Start Sector    Num Sectors     UUID            Type
  1     128             386656          00000000-01     0c Boot
  2     386784          7346464         00000000-02     83
=> 

Kernel Boot:

[    0.000000] Kernel command line: console=ttyO2,115200n8 root=PARTUUID=00bc614e-02 rw rootfstype=ext4 rootwait console=ttyO2,115200n8 vram=12M omapfb.vram=0:8M,1:4M omapfb.rotate_type=0 omapdss.def_disp=lcd rootwait twl4030_charger.allow_usb=1 musb_hdrc.preserve_vbus=1 log_buf_len=8M ignore_loglevel earlyprintk

This means the PARTUUID mechanism *is* working. It is only that I have no unique IDs on the SD cards!

So it is really a bug in creating SD cards by makesd. This should be easy to fix.

Thanks for all comments which show again that group work is superior to work in a hidden chamber...

BR,
Nikolaus



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