Making own uImage

[ineiti]

Hello everybody,

happy new year - I'm trying to make my own uImage (to insert some custom hooks) on a Smileplug. However, I don't understand how I'm supposed to fit it together. By installing linux-mvebu-smileplug and linux-mvebu, I get the uImage and zImage file. By reading PKGSOURCE I think that

$this->bbcode_second_pass_code('', 'mkimage( zImage + dtb ) => uImage')

is that correct? Where does mkinitcpio come in? Does it create a zImage? Then why are these different?

$this->bbcode_second_pass_code('', '# file /boot/zImage.created_from_mkinitcpio
/boot/zImage.created_from_mkinitcpio: ASCII cpio archive (SVR4 with no CRC)
# file /boot/zImage
/boot/zImage: floppy with old FAT filesystem, Media descriptor 0xfb
')

Help! I'm lost...

Linus

[pepedog]

Are you getting the info from https://github.com/archlinuxarm/PKGBUIL ... u/PKGBUILD ?

[ineiti]

Yes, I looked at that. I did find the line

$this->bbcode_second_pass_code('', 'make ${MAKEFLAGS} zImage modules dtbs
')

which makes me think (hope) that some special mkinitcpio-thingie is happening in the Linux-kernels. But I haven't compiled one in years (I think I even left out the 2.6-series , and downloading 70MB is slow over 64kbps... So instead of hacking around, I was hoping for a quick answer...

The other lines I found are

$this->bbcode_second_pass_code('', '  cat arch/$KARCH/boot/zImage arch/$KARCH/boot/dts/armada-370-smileplug.dtb > myimage
  mkimage -A arm -O linux -T kernel -C none -a 0x00008000 -e 0x00008000 -n "${pkgname}" -d myimage "${pkgdir}/boot/uImage"
')

Which I interpreted as

$this->bbcode_second_pass_code('', 'mkimage( zImage + dtb )')

But I'm not sure how the kernel-Makefile creates the zImage! In fact I just searched through the linux-source (lxr-sites) and didn't find any reference to mkinitcpio. Aww crap, next time I buy Windows-compatible stuff and then when it doesn't work just complain that if this would be open-source, I could hack it myself

[pepedog]

I think you are confusing things, mkinitcpio makes a ram device, generally we don't use them
Most arm just make uImage does the job, but this device needs device tree appended, it's a new way to define what devices and settings are needed, mkimg is just a wrapping tool

[moonman]

what exactly are you trying to accomplish?

initrd = initial ramdiak with some bits from rootfs to load the drivers/check fs before the actual rootfs is mounted, like pepedog said we don't use it before kernels already have all the necessary stuff built it, but you can use it if you need to.
uImage = actual kernel image for u-boot

[ineiti]

Yes, I'm sure I'm confusing things But I'd like to clear things up. So, you say

The zImage is just the kernel
The uImage is the kernel and the DT
mkinitcpio is not used at all - no ramdisk

So all my efforts with mkinitcpio were in fact in vain Thanks for clearing things up! So you could remove the "mkinitcpio"-dependency in the kernels?

[WarheadsSE]

Well, then if people wanted to use an initrd they made since we don't supply one, they'd be stuck a bit.