u-boot and zImage

> Now, I am wondering if that's possible to download the zImage directly with u-boot.

You can download it, and program it in ram, but you can't boot it using bootm.

The 'bootm' command requires a valid u-boot image.

> Don't mkimage zImage, it is already compressed.

Compression has absolutely _nothing_ to do with mkimage. The mkimage utility

is necessary to properly boot a kernel image using u-boot, regardless of whether

or not the kernel is compressed. mkimage simply adds (prepends) a header to the

kernel (or filesystem, or script, etc). The header contains information such as load

address, entrypoint address, a header CRC-32, data CRC-32, and yes ... a field

that indicates if the data (the kernel) is compressed.

When the kernel is compressed via the kernel build scripts, you should tell

mkimage that kernel has compression 'None'.

> I guess I got to transform the zImage with mkimage before downloading it

> with tftpboot.

Correct.

> Why do you program the flash with u-boot? It is not the right way. Use the

> nios2-flash-programmer to program the flash

Don't be silly! Programming flash with u-boot is one of its most useful features.

It is perfectly appropriate (and correct) to do so -- especially when you do not

want to require xxxBlaster and an exposed JTAG header.

Additionally, if you load your flash image using TFTP, it is _much_, _much_ faster.

Furthermore, u-boot has been programming flash memory on more architectures

for a _much_ longer time than the "flash-programmer".

> You should use u-boot to download program via tftp to sdram and run. That

> should be most people want u-boot to do.

I have been working with u-boot for for well over 7 years now. I've done at least a

dozen board ports using four different architectures. I can tell you from experience,

_most_ systems use u-boot to boot a kernel that is stored in flash. The TFTP feature

is used to perform field upgrades (and for testing during development).

> And if I can do all that things with u-boot only, why bothering myself with

> other tools !

Exactly! With u-boot you can do almost everything using something as primitive

as a UART interface and some cheap terminal software. Or as sophisticated as

loading and executing a script via NFS, that in turn loads a kernel image via

tftp that gets loaded into flash and eventually booted ... phew ;-)

Regards,

--Scott