User:Parasense/arm

OMAP5 uEVM notes

Fedora 20 uENV.txt:

setenv bootm_size 0x20000000
setenv bootargs console=${console} vram=${vram} root=LABEL=_/ ro rootwait rhgb
ext4load mmc 0:3 0x82000000 /boot/vmlinuz-3.14.0-0.rc6.git4.1.fc21.armv7hl
ext4load mmc 0:3 0x88080000 /boot/uInitrd-3.14.0-0.rc6.git4.1.fc21.armv7hl
ext4load mmc 0:3 0x88000000 /boot/dtb-3.14.0-0.rc6.git4.1.fc21.armv7hl/omap5-uevm.dtb
bootz 0x82000000 0x88080000 0x88000000

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Fedora 21/rawhide notes

Install MLO and u-boot on non-vfat image: WARNING: BETA NOTES

sudo dd if=MLO           \
        of=/dev/sdz      \
      conv=fsync,notrunc \
      seek=128k

sudo dd if=u-boot.img    \
        of=/dev/sdz      \
     count=2             \
      seek=1             \
      conv=notrunc,fsync \
        bs=384k

F20 notes

• download the f20 minimal image

wget http://download.fedoraproject.org/pub/fedora/linux/releases/20/Images/armhfp/Fedora-Minimal-VFAT-armhfp-20-1-sda.raw.xz

• Decompress

unxz -v Fedora-Minimal-VFAT-armhfp-20-1-sda.raw.xz

• Map the partitions

kpartx -avp _fedora_  Fedora-Minimal-VFAT-armhfp-20-1-sda.raw

• Extract the rootfs

dd if=/dev/mapper/loop0_fedora_3 \
   of=f20-minimal-rootfs.ext4    \
 conv=fsync

• Unmap the partitions

kpartx -dvp _fedora_  Fedora-Minimal-VFAT-armhfp-20-1-sda.raw

• Optionally discard the official Fedora minimal image, we now have the essential rootfs.

• Shrink the rootfs image file

e2fsck    -f  f20-minimal-rootfs.ext4 &> /dev/null
resize2fs -M  f20-minimal-rootfs.ext4

• Create a new f20 disk image file

truncate -s 4G f20-minimal.disk

• Partition the newly created disk image

parted -a    optimal 
       -s -- f20-minimal.disk      \
             unit MiB              \
             mklabel msdos         \
             mkpart primary 4 24   \
             mkpart primary 24 152 \
             mkpart primary 152 -1 \
             print

• Map the partitions to loop devices

kpartx -avp _remix_ f20-minimal.disk

• Format the partitions accordingly to the output of the previous kpartx cmd.

mkfs.vfat -n uboot -F 16              /dev/mapper/loop0_remix_1

mkswap -L swap -U $(uuidgen)          /dev/mapper/loop0_remix_2

#mkfs.ext4 -L rootfs -U $(uuidgen) -m0 /dev/mapper/loop0_remix_3

• Copy the Fedora-20 minimal rootfs to the appropriate partition

dd if=f20-minimal-rootfs.ext4   \
   of=/dev/mapper/loop0_remix_3 \
   bs=4M conv=fsync 

• Inflate the rootfs on the partition

resize2fs -fp /dev/mapper/loop0_remix_3

• Unmap the partition loops devs

kpartx -dvp _remix_ f20-minimal.disk

Tips & Tricks

You can monitor the DD command in an easy one liner.

dd if=/dev/sdc3 of=f20-minimal-rootfs.ext4-ORIG &   while ps -p $! ; do kill -USR1 $! ; sleep 5 ; done

Use fsync with DD to avoid potentially dangerous filesystem buffer cache issues. My computers have large amounts of memory, and it is possible an entire file would be buffered into filesystem cache. The effect is the DD write operation appearing to finish very fast, but the filesystem empty the buffer/cache in the background asynchronously. This is like typing "sync" after the DD command, but instead happens during writes.

dd if=/dev/foo
   of=/dev/bar
 conv=[fsync|fdatasync]

This signals the DD process to spew progress info every five seconds. Especially useful on very slow sdcard, or large data transfers.

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