download kernel into ram by u-boot

Hi smalllight,

> I want to download the kernel to the sdram by u-boot.

First, create a u-boot image file with mkimage.

> how can I use the tftp in u-boot?

Try the u-boot command:

==> help tftpboot

The syntax is: tftpboot address fname

Example: download the file "foo.img" to address 0x400

==> tftpboot 400 foo.img

Then to boot the kernel:

==> bootm 400

Regards,

--Scott

1. Could we use tftp sever in u-boot ?

2. How to enable tftp server or tftp client ? Such as# define in <include>/<configs>/<board>.h, as we hasn&#39;t finish the net device(dm9000a) driver. We are still studying the source tree of u-boot and <u-boot>/readme.

3. Maybe there are two ways to boot linux:

(1) like smcnutt: use mkimage to compress the linux; tftp client down at proper SDRAM&#39;s address; bootm;

(2) tftp down the vmlinux.bin to 0x0 of SDRAM, "jump 0x0"

Let&#39;s verify them by ourselves, too.

Thank you in advance.

Hi mountain8848,

> Could we use tftp sever in u-boot ?

u-boot implements tftp client only.

> How to enable tftp server or tftp client ?

Enable the network commands in the CONFIG_COMMANDS macro by adding

CFG_CMD_NET.

> tftp down the vmlinux.bin to 0x0 of SDRAM, "jump 0x0"

I do not recommend doing this ... in most configurations, you&#39;ll overwrite the

exception trampoline, so you won&#39;t even finish the tftp download ... a timer

interrupt will occur during the download and you&#39;ll jump to a bogus address.

The best bet is to just use mkimage with a compressed kernel. Load the kernel

somewhere high in sdram, then use bootm ... which will disable interrupts,

decompress the kernel to its runtime address, then jump to the entry point.

You can configure u-boot to tftpboot the kernel automatically at startup

by setting the boot command environment variable. In fact, you can configure

u-boot to load an execute a full script (hush parser) that does many things

at startup.

Regards,

--Scott

Hi smcnutt,

We finished the net device(dm9000a) driver in u-boot. And debuging tftpboot

1.

=>tftpboot 01500000 vmlinux.img

// SDRAM base address: 0100 0000

// SDRAM size : 0100 0000 (16MB)

After succesfully download the vmlinux.img, U-boot can&#39;t return to "console" state(cannot get &#39;==>&#39;) ? We cannot type "bootm" command.

2.

in <u-boot>/net/net.c L:528

Before

switch (NetState) {....

, We add

printf(" T T T ");

,

the result is that the net speed is faster than before.

We guess the reason is that:

u-boot send a "request";printf() add a little delay to meet u-boot receive it properly, isn&#39;t it ? Ping command can&#39;t work without printf(" t t t ") Delay, neither. Dose any good idea to solve speed/delay problem.

Hi mountain8848,

Sounds like a timer configuration issue. Check your config file to make sure the

timer macros are set correctly for your hardware configuration. Specifically,

check:

CFG_NIOS_TMRMS - the number of milliseconds per interrupt.

CFG_NIOS_TMRCNT - define this if you want to change the timer count register (e.g. to

slow down a high res timer).

CFG_HZ - the timer frequency.

In general, I recommend 10 msec or higher for the u-boot timer. There&#39;s usually

no need for anything faster in a bootloader ;-)

BTW: you can get a real rough estimate of your interrrupt period by simply using

the u-boot &#39;irq&#39; command -- to view the number of interrupts over a period of time.

It&#39;s handy for simple estimates -- like making sure you&#39;re not off by a factor of 10.

Regards,

--Scott