[RFC] New target 'cuImage' - compatibility uImage

Wolfgang Denk wd at denx.de
Fri Aug 4 06:00:43 EST 2006

In message <1154618945.5094.6.camel at localhost> you wrote:
> > In my understanding, an "uImage" file is a  image  consisting  of  an
> > U-Boot  header (64 bytes) followed by an (compressed or uncompressed)
> > Linux kernel image.
> Yes


> I mean that the data contained within the uImage is compressed. In this

This is only one option. Some configurations  prefer  to  use  uncom-
pressed images because these canbe booted faster.

> case where the uImage data is compressed I choose to skip compressing
> the kernel section in the zImage (because have it compressed twice was
> wasteful)

We don't use zImage !

> So to clarify. The current method has a zImage with a compressed kernel

No, it does not. We do  not  use  zImage  (which  includes  bootstrap
wrapper  code).  U-Boot  uses  a plain stripped and compressed kernel
image, i. e. something like this:

	objcopy  -O binary vmlinux vmlinux.bin
	gzip -f -9 <vmlinux.bin >vmlinux.gz
	mkimage ... -C gzip -d vmlinux.gz uImage

> section where the actual kernel lives. The zImage uncompressed this code
> to the kernel load address. The 'cuImage' would be packaged in a uImage
> with the entire zImage compressed, except in this case the kernel
> section would not be compressed (to avoid have a compressed image within
> a compressed image)

You would have to create a new image type which has  executable  code
at the start and carries the kernel image as payload, similar to what
zImage does. 

Best regards,

Wolfgang Denk

Software Engineering:  Embedded and Realtime Systems,  Embedded Linux
Phone: (+49)-8142-66989-10 Fax: (+49)-8142-66989-80 Email: wd at denx.de
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