Sorry not finished and accidentally hit "send". But if you need more information on the steps. I can test, and duplicate exact step in order for you to do the same - In a safe way.
On Thu, Oct 8, 2015 at 2:19 PM, William Hermans <[email protected]> wrote: > *Sorry that this is probably a dumb question, but is it possible to not >> blow* >> * away the partition table since I just want to swap the MLO and >> u-boot.img?* > > > *Read everything below before half fast attempting such procedure* > > If I understand what you're asking here, yes it is possible. I've > experimented with this personally. I talk about what I've done here in a > blog post. > http://www.embeddedhobbyist.com/2015/09/beaglebone-black-working-with-debianlinux-images/ > > So here is the idea. > > First you would want to backup the MBR liek this: $ sudo dd if=/dev/sdb of > =/home/william/mbr-sdb.bak bs=1M count=1 > > Second You write the wanted MLO / uboot.img file into the first 512k of > the MBR. As demonstrated on Roberts eewiki guide - Which I think you linked > to already ? > > That *should* leave the partition table intact. But in case it fails, you > can put the whole partition table, plus original MLO, and uboot.image back > on the sdcard like so. > > $ sudo dd if=/home/william/mbr-sdb.bak of=/dev/sdb bs=1M count=1 > > *OR* > > It would probably be safer / easier to just dd the whole block device into > an image file stored in a safe place. > > On Thu, Oct 8, 2015 at 1:57 PM, Robert Nelson <[email protected]> > wrote: > >> On Thu, Oct 8, 2015 at 3:37 PM, Christopher Stack <[email protected]> >> wrote: >> > Sorry that this is probably a dumb question, but is it possible to not >> blow >> > away the partition table since I just want to swap the MLO and >> u-boot.img? >> >> Using dd, just re-write them to the microSD... The partition table is >> safe at another location.. >> >> > >> > I'm just running the standard image on a Beagle Bone Black that does not >> > have an eMMC or hdmi chip. I assumed it was busy because I was trying to >> > reprogram the disk while on an OS that was using the disk? >> > >> > This was the error: >> > >> > >> > >> > Checking that no-one is using this disk right now ... >> > BLKRRPART: Device or resource busy >> > >> > >> > >> > >> > >> > >> > After adding the force option it said: >> > >> > >> > >> > >> > Checking that no-one is using this disk right now ... >> > BLKRRPART: Device or resource busy >> > >> > This disk is currently in use - repartitioning is probably a bad idea. >> > Umount all file systems, and swapoff all swap partitions on this disk. >> > Use the --no-reread flag to suppress this check. >> > >> > Disk /dev/mmcblk0: 121008 cylinders, 4 heads, 16 sectors/track >> > >> > sfdisk: ERROR: sector 3069576189 does not have an msdos signature >> > /dev/mmcblk0: unrecognized partition table type >> > Old situation: >> > No partitions found >> > New situation: >> > Units = mebibytes of 1048576 bytes, blocks of 1024 bytes, counting from >> 0 >> > >> > Device Boot Start End MiB #blocks Id System >> > /dev/mmcblk0p1 * 1 3780 3780 3870720 83 Linux >> > /dev/mmcblk0p2 0 - 0 0 0 Empty >> > /dev/mmcblk0p3 0 - 0 0 0 Empty >> > /dev/mmcblk0p4 0 - 0 0 0 Empty >> > Successfully wrote the new partition table >> >> ah, sfdisk is just noisly, it worked ^^^^... >> >> > Re-reading the partition table ... >> > BLKRRPART: Device or resource busy >> >> later versions don't show this extra stuff... >> >> > >> > >> > >> > >> > >> > I have the serial output after the last test, but not from the test >> where I >> > did not recreate the partition table. >> > >> > >> > >> > >> > U-Boot 2015.10-rc2-00001-g5879130-dirty (Oct 09 2015 - 15:52:49 +0000) >> > >> > Watchdog enabled >> > I2C: ready >> > DRAM: 512 MiB >> > Reset Source: Global external warm reset has occurred. >> > Reset Source: Power-on reset has occurred. >> > MMC: OMAP SD/MMC: 0, OMAP SD/MMC: 1 >> > Using default environment >> > >> > Net: <ethaddr> not set. Validating first E-fuse MAC >> > cpsw >> > Hit any key to stop autoboot: 0 >> > gpio: pin 53 (gpio 53) value is 1 >> > switch to partitions #0, OK >> > mmc0 is current device >> > gpio: pin 54 (gpio 54) value is 1 >> > Checking for: /uEnv.txt ... >> > Checking for: /boot.scr ... >> > Checking for: /boot/boot.scr ... >> > Checking for: /boot/uEnv.txt ... >> > ** Invalid partition 2 ** >> > ** Invalid partition 3 ** >> > ** Invalid partition 4 ** >> > ** Invalid partition 5 ** >> > ** Invalid partition 6 ** >> > ** Invalid partition 7 ** >> >> This looks fine, based on where you stopped... it was searching for >> the microSD card... >> >> Regards, >> >> -- >> Robert Nelson >> https://rcn-ee.com/ >> >> -- >> For more options, visit http://beagleboard.org/discuss >> --- >> You received this message because you are subscribed to the Google Groups >> "BeagleBoard" group. >> To unsubscribe from this group and stop receiving emails from it, send an >> email to [email protected]. >> For more options, visit https://groups.google.com/d/optout. >> > > -- For more options, visit http://beagleboard.org/discuss --- You received this message because you are subscribed to the Google Groups "BeagleBoard" group. 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