Gumstix User Wiki - User contributions [en]

Making qemu images

2008-08-06T10:03:48Z

MatthieuHerrb: use only ext2 in the example, as default kernels only support ext3 through a module.

= Preparing flash / disk images for qemu =

== Flash images ==

The flash image emulates the flash memory on the Gumstix motherboard. It's a single file that has the size of the emulated flash memory (32MB in the case of the verdex board emulated by qemu). It will contain the same images as the real flash, at the same offsets:

* The u-boot image at offset 0
* The root file system image at offset 256kB
* The kernel image at the end of the image offset 31MB

The following 3 files are needed

* <tt>u-boot-verdex-400-r1587.bin</tt> - u-boot
* <tt>gumstix-basic-image-gumstix-custom-verdex.jffs2</tt> - root file system
* <tt>uImage-2.6.21-r1-gumstix-custom-verdex.bin</tt> - kernel.

Except for the u-boot image which is not yet built by openembedded, those files can be found in the <tt>tmp/deploy/glibc/images/</tt> sub-directory of <tt>gumstix-oe</tt> after running bitbake.

To assemble the image <tt>flash.img</tt> run the following commands:

dd of=flash.img bs=128k count=256 if=/dev/zero
dd of=flash.img bs=128k conv=notrunc if=u-boot-verdex-400-r1587.bin
dd of=flash.img bs=128k conv=notrunc seek=2 if=gumstix-basic-image-gumstix-custom-verdex.jffs2
dd of=flash.img bs=128k conv=notrunc seek=248 if=uImage-2.6.21-r1-gumstix-custom-verdex.bin

== mmc/CF images ==

Those images are used to emulate the flash memory cards that are present on netmicroSD, netMMC, netCF... expansion boards. It is possible to
boot from them or just to store more data in them.

On the Linux host, the <tt>losetup</tt>(1) utility is used to access those images as real block devices,

/!\ The current qemu version seems to be limited to 1GB card images. The examples presented here will thus use 1GB images.

* Creating the empty image

dd of=mmc.img bs=1M count=1024 if=/dev/zero

* Creating a block device for the whole image

losetup /dev/loop0 mmc.img

* Running fdisk to partition the card

fdisk /dev/loop0

=== Partitionning the card ===

In the most simple case, one single partition (VFAT, ext2 or ext3) can cover the whole card. However, in order to boot from the card and use it for the root file system, at least 2 partitions, one small VFAT to hold the kernel and the u-boot script, and a bigger one, ext2 for the root file system. The folloing example shows a basic setup (using fdisk 'p' command):

<pre>
Command (m for help): p

Disk /dev/loop0: 1073 MB, 1073741824 bytes
255 heads, 63 sectors/track, 130 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Disk identifier: 0x25c4dea4

Device Boot Start End Blocks Id System
/dev/loop0p1 1 7 56196 6 FAT16
/dev/loop0p2 8 130 987997+ 83 Linux
</pre>

=== Accessing the partitions ===

In order to access the partitions, 2 more loop devices have to be created with losetup. The offsets into the main loop device (<tt>/dev/loop0</tt>) need to be specified. For this, use <tt>fdisk -ul</tt> to find the starting block of your partitions:
<pre>

Disk /dev/loop0: 1073 MB, 1073741824 bytes
255 heads, 63 sectors/track, 130 cylinders, total 2097152 sectors
Units = sectors of 1 * 512 = 512 bytes
Disk identifier: 0x25c4dea4

Device Boot Start End Blocks Id System
/dev/loop0p1 63 112454 56196 6 FAT16
/dev/loop0p2 112455 2088449 987997+ 83 Linux
</pre>

Partition 1 starts at block 63 (which is 63*512 = 32256 bytes) and partition 2 starts at block 112455 (which is 112455*512 = 57576960 bytes).

The following commands will then create the 2 loop devices:

losetup -o 32256 /dev/loop1 /dev/loop0
losetup -o 57576960 /dev/loop2 /dev/loop0

/dev/loop1 and /dev/loop2 will now access the 2 partitions.

=== Formatting and mounting ===

mkfs -t vfat /dev/loop1
mkfs -t ext2 /dev/loop2

mkdir /mnt/1
mkdir /mnt/2

mount /dev/loop1 /mnt/1
mount /dev/loop2 /mnt/2

=== Copying data ===

The kernel image (called <tt>uImage</tt> on the docs on using root on MMC/SD), the u-boot script <tt>gumstix-factory.script</tt> are needed on /mnt/1.

To transfer the root filesystem to /mnt/2, un-tar the <tt>gumstix-basic-image-gumstix-custom-verdex.tar.gz</tt> found in the <tt>tmp/deploy/glibc/images/gumstix-custom-verdex/</tt> directory.

=== Cleaning up ===

Before starting qemu, both partitions should be un-monted and the 3 loop devices should be un-configured. Failing to do that will almost certainly corrupt the images.

umount /mnt/2
umount /mnt/1
losetup -d /dev/loop2
losetup -d /dev/loop1
losetup -d /dev/loop0

[[Category:How_to_-_qemu]]

Making qemu images

2008-07-31T12:55:12Z

MatthieuHerrb: info on mmc/CF images.

= Preparing flash / disk images for qemu =

== Flash images ==

The flash image emulates the flash memory on the Gumstix motherboard. It's a single file that has the size of the emulated flash memory (32MB in the case of the verdex board emulated by qemu). It will contain the same images as the real flash, at the same offsets:

* The u-boot image at offset 0
* The root file system image at offset 256kB
* The kernel image at the end of the image offset 31MB

The following 3 files are needed

* <tt>u-boot-verdex-400-r1587.bin</tt> - u-boot
* <tt>gumstix-basic-image-gumstix-custom-verdex.jffs2</tt> - root file system
* <tt>uImage-2.6.21-r1-gumstix-custom-verdex.bin</tt> - kernel.

Except for the u-boot image which is not yet built by openembedded, those files can be found in the <tt>tmp/deploy/glibc/images/</tt> sub-directory of <tt>gumstix-oe</tt> after running bitbake.

To assemble the image <tt>flash.img</tt> run the following commands:

dd of=flash.img bs=128k count=256 if=/dev/zero
dd of=flash.img bs=128k conv=notrunc if=u-boot-verdex-400-r1587.bin
dd of=flash.img bs=128k conv=notrunc seek=2 if=gumstix-basic-image-gumstix-custom-verdex.jffs2
dd of=flash.img bs=128k conv=notrunc seek=248 if=uImage-2.6.21-r1-gumstix-custom-verdex.bin

== mmc/CF images ==

Those images are used to emulate the flash memory cards that are present on netmicroSD, netMMC, netCF... expansion boards. It is possible to
boot from them or just to store more data in them.

On the Linux host, the <tt>losetup</tt>(1) utility is used to access those images as real block devices,

/!\ The current qemu version seems to be limited to 1GB card images. The examples presented here will thus use 1GB images.

* Creating the empty image

dd of=mmc.img bs=1M count=1024 if=/dev/zero

* Creating a block device for the whole image

losetup /dev/loop0 mmc.img

* Running fdisk to partition the card

fdisk /dev/loop0

=== Partitionning the card ===

In the most simple case, one single partition (VFAT, ext2 or ext3) can cover the whole card. However, in order to boot from the card and use it for the root file system, at least 2 partitions, one small VFAT one to hold the kernel and the u-boot script, and the other one, ext2 or 3 for the root file system. The folloing example shows a basic setup (using fdisk 'p' command):

<pre>
Command (m for help): p

Disk /dev/loop0: 1073 MB, 1073741824 bytes
255 heads, 63 sectors/track, 130 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Disk identifier: 0x25c4dea4

Device Boot Start End Blocks Id System
/dev/loop0p1 1 7 56196 6 FAT16
/dev/loop0p2 8 130 987997+ 83 Linux
</pre>

=== Accessing the partitions ===

In order to access the partitions, 2 more loop devices have to be created with losetup. The offsets into the main loop device (<tt>/dev/loop0</tt>) need to be specified. For this, use <tt>fdisk -ul</tt> to find the starting block of your partitions:
<pre>

Disk /dev/loop0: 1073 MB, 1073741824 bytes
255 heads, 63 sectors/track, 130 cylinders, total 2097152 sectors
Units = sectors of 1 * 512 = 512 bytes
Disk identifier: 0x25c4dea4

Device Boot Start End Blocks Id System
/dev/loop0p1 63 112454 56196 6 FAT16
/dev/loop0p2 112455 2088449 987997+ 83 Linux
</pre>

Partition 1 starts at block 63 (which is 63*512 = 32256 bytes) and partition 2 starts at block 112455 (which is 112455*512 = 57576960 bytes).

The following commands will then create the 2 loop devices:

losetup -o 32256 /dev/loop1 /dev/loop0
losetup -o 57576960 /dev/loop2 /dev/loop0

/dev/loop1 and /dev/loop2 will now access the 2 partitions.

=== Formatting and mounting ===

mkfs -t vfat /dev/loop1
mkfs -t ext3 /dev/loop2

mkdir /mnt/1
mkdir /mnt/2

mount /dev/loop1 /mnt/1
mount /dev/loop2 /mnt/2

=== Copying data ===

The kernel image (called <tt>uImage</tt> on the docs on using root on MMC/SD), the u-boot script <tt>gumstix-factory.script</tt> are needed on /mnt/1.

To transfer the root filesystem to /mnt/2, un-tar the <tt>gumstix-basic-image-gumstix-custom-verdex.tar.gz</tt> found in the <tt>tmp/deploy/glibc/images/gumstix-custom-verdex/</tt> directory.

=== Cleaning up ===

Before starting qemu, both partitions should be un-monted and the 3 loop devices should be un-configured. Failing to do that will almost certainly corrupt the images.

umount /mnt/2
umount /mnt/1
losetup -d /dev/loop2
losetup -d /dev/loop1
losetup -d /dev/loop0

[[Category:How_to_-_qemu]]

Making qemu images

2008-07-31T10:17:08Z

MatthieuHerrb: Intructions on building a flash image for gumstix

U-Boot scripts

2008-07-31T09:38:13Z

MatthieuHerrb: try again

= Modifying U-Boot scripts =

The main useful script is gumstix-factory.script which, if found on the MMC or CF card will be executed during boot.

To generate a u-boot script that's executable, it has to be packed into an u-boot image using mkimage.

Use your favorite text editor to create gumstix-factory.script.source, and then run the following command to generate the image:

mkimage -A arm -O linux -T script -C none -a 0 -e 0 -n gumstix-factory.script -d gumstix-factory.script.source gumstix-factory.script

[[Category:How_to_-_linux]]

U-Boot scripts

2008-07-31T09:36:44Z

MatthieuHerrb: fix category

U-Boot scripts

2008-07-31T09:35:17Z

MatthieuHerrb: information on how to create a u-boot script