[U-Boot-Users] Where does u-boot start when booting Linux?

[U-Boot-Users] Where does u-boot start when booting Linux?

[Allen Curtis]

I was hoping that someone could give me a quick answer. When u-boot starts 
Linux, does is start from the beginning for does it jump in somewhere past 
decompress()?

I have been looking at the Linux code and it doesn't appear that the bdinfo 
structure is being handled correctly for u-boot. There is an 
CONFIG_EMBEDDEDBOOT option but even this only passes the boot parameter in 
a few instances. Does u-boot fix this somehow?

Another thing is embed_config() for the ADS8260 board, forces the baud-rate 
to 9600 but 2_4_devel is quite happy at 115200 as in u-boot. This is 
interesting since I am trying to fix a serial baud-rate problem.

TIA!

[U-Boot-Users] Where does u-boot start when booting Linux?

[Wolfgang Denk]

In message <6.0.0.22.2.20031014070537.032b4bd0@192.168.1.10> you wrote:
> I was hoping that someone could give me a quick answer. When u-boot starts 
> Linux, does is start from the beginning for does it jump in somewhere past 
> decompress()?

There no decompress() in the Linux kernel. So  U-Boot  always  starts
the Linux kernel right from the beginning.

> I have been looking at the Linux code and it doesn't appear that the bdinfo 
> structure is being handled correctly for u-boot. There is an 
> CONFIG_EMBEDDEDBOOT option but even this only passes the boot parameter in 
> a few instances. Does u-boot fix this somehow?

I think you are  looking  at  the  wrong  place.  Don;t  mistake  the
bootstrap  loader  for  a  part of theLinux kernel. We don;t use this
stuff at all.

> Another thing is embed_config() for the ADS8260 board, forces the baud-rate 
> to 9600 but 2_4_devel is quite happy at 115200 as in u-boot. This is 
> interesting since I am trying to fix a serial baud-rate problem.

All this stuff is completely irrelevant when using U-boot.

Best regards,

Wolfgang Denk

-- 
Software Engineering:  Embedded and Realtime Systems,  Embedded Linux
Phone: (+49)-8142-4596-87  Fax: (+49)-8142-4596-88  Email: wd at denx.de
It may be that your whole purpose in life is simply  to  serve  as  a
warning to others.

[U-Boot-Users] Where does u-boot start when booting Linux?

[Allen Curtis]

At 07:47 AM 10/14/03, Wolfgang Denk wrote:
>In message <6.0.0.22.2.20031014070537.032b4bd0@192.168.1.10> you wrote:
> > I was hoping that someone could give me a quick answer. When u-boot starts
> > Linux, does is start from the beginning for does it jump in somewhere past
> > decompress()?
>
>There no decompress() in the Linux kernel. So  U-Boot  always  starts
>the Linux kernel right from the beginning.

When compiling 82xx or 8xx kernels, you always get arch/ppc/boot/simple.

> > I have been looking at the Linux code and it doesn't appear that the 
> bdinfo
> > structure is being handled correctly for u-boot. There is an
> > CONFIG_EMBEDDEDBOOT option but even this only passes the boot parameter in
> > a few instances. Does u-boot fix this somehow?
>
>I think you are  looking  at  the  wrong  place.  Don;t  mistake  the
>bootstrap  loader  for  a  part of theLinux kernel. We don;t use this
>stuff at all.

I think I understand. For a very long time now I have been using 
zImage.embedded for booting. When I followed the u-boot instructions I used 
"vmlinux" which doesn't contain the boot loader. Right?

> > Another thing is embed_config() for the ADS8260 board, forces the 
> baud-rate
> > to 9600 but 2_4_devel is quite happy at 115200 as in u-boot. This is
> > interesting since I am trying to fix a serial baud-rate problem.
>
>All this stuff is completely irrelevant when using U-boot.

Thanks for the info. It has pointed me in a new direction. The problem I am 
having is the serial baud-rate is fine in u-boot but wrong when the kernel 
boots. Perhaps the clock dividers are setup differently by u-boot than 
expected by the 8260 implementation?

Suggestions welcome.

Thanks again!

[U-Boot-Users] Where does u-boot start when booting Linux?

[Wolfgang Denk]

In message <6.0.0.22.2.20031014083032.02837c80@192.168.1.10> you wrote:
>
> >There no decompress() in the Linux kernel. So  U-Boot  always  starts
> >the Linux kernel right from the beginning.
> 
> When compiling 82xx or 8xx kernels, you always get arch/ppc/boot/simple.

What do you mean with "you get it"? It comes with  the  source,  yes.
But you don't have to use it.

> I think I understand. For a very long time now I have been using 
> zImage.embedded for booting. When I followed the u-boot instructions I used 
> "vmlinux" which doesn't contain the boot loader. Right?

Right. vmlinux does not contain the bootstral loader,  all  functions
of which are already present in U-Boot.

> Thanks for the info. It has pointed me in a new direction. The problem I am 
> having is the serial baud-rate is fine in u-boot but wrong when the kernel 
> boots. Perhaps the clock dividers are setup differently by u-boot than 
> expected by the 8260 implementation?

Perhaps you don;t pass the baud-rate  to  the  kernel?  Did  you  try
passing something like "console=ttyS0,$(baudrate)" ?

Best regards,

Wolfgang Denk

-- 
Software Engineering:  Embedded and Realtime Systems,  Embedded Linux
Phone: (+49)-8142-4596-87  Fax: (+49)-8142-4596-88  Email: wd at denx.de
Fascinating is a word I use for the unexpected.
	-- Spock, "The Squire of Gothos", stardate 2124.5

[U-Boot-Users] Where does u-boot start when booting Linux?

[Allen Curtis]

> > Thanks for the info. It has pointed me in a new direction. The problem I
> > am having is the serial baud-rate is fine in u-boot but wrong when the
> > kernel boots. Perhaps the clock dividers are setup differently by u-boot
> > than expected by the 8260 implementation?
>
> Perhaps you don;t pass the baud-rate  to  the  kernel?  Did  you  try
> passing something like "console=ttyS0,$(baudrate)" ?

I tried:
setenv bootargs root=/dev/nfs rw console=ttyS0,115200
tftpboot 100000 /tftpboot/mpc8266.uImage
bootm 100000

When Linux boots it just prints "." instead of text.

[U-Boot-Users] Where does u-boot start when booting Linux?

[Wolfgang Denk]

Dear Allen,

in message <200310141333.32991.acurtis@onz.com> you wrote:
> 
> I tried:
> setenv bootargs root=/dev/nfs rw console=ttyS0,115200
> tftpboot 100000 /tftpboot/mpc8266.uImage
> bootm 100000
> 
> When Linux boots it just prints "." instead of text.

And what does a post-mortem dump of "log_buf" show?

Best regards,

Wolfgang Denk

-- 
Software Engineering:  Embedded and Realtime Systems,  Embedded Linux
Phone: (+49)-8142-4596-87  Fax: (+49)-8142-4596-88  Email: wd at denx.de
Oh, that sound of male ego.  You travel halfway across the galaxy and
it's still the same song.
	-- Eve McHuron, "Mudd's Women", stardate 1330.1