Informations about mem and proc environment between bootloader and kernel

Informations about mem and proc environment between bootloader and kernel

[fabien boucher]

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And I need some help for my project (I'm in internship) to port linux on a
custom board.
This board has been developped by the company where i'm doing the intership
and it's
based on a MPC875 with RAM and Flash chips and several other devices.
Currently the board run with a BSP developped
by the company's developpers, the BSP launch Psos.
This BSP is able to decompress an image and load it in RAM.
I plan to use U-boot to be more able to boot a kernel but as it's not a
common
board so it's not initialy supported by U-boot. So I have two choices first
use the BSP with some changes to adapt it for loading the Linux kernel or
using U-boot.
I'm looking for informations about the memory and processor environment
needed by linux to
boot properly for evaluate whether the use of a customize BSP is the easiest
way against
the port of a new board under U-boot. So if someone know where i can found
those informations
concerning the step between where the boot program have control of the cpu
and where Linux
take control.

Thank you,
Fabien

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Re: Informations about mem and proc environment between bootloader and kernel

[raul.moreno]

Hello Fabien,

you should download the U-boot sources from sourceforge.net. There is a=

README file there where you can read about porting U-boot.
The porting to a custom board of U-boot is easier when your cpu is incl=
ude,
like in your case (mpc8xx). Basically you have to create a new entry in=

board directory. There you have to insert the initialization code for y=
our
flash, sdram and other devices. You also have to make a file as the one=
s in
/include/configs/ with your configuration board.

It is essential to have correct environment variables when Linux takes =
the
control.
If you use the u-boot command "bootm" in order to boot Linux, the file
where U-Boot transfer the control to Linux is /common/cmd_bootm.c.

Moreover I would recommend you a book which explains many things regard=
ing
porting Linux (and U-boot):
Embedded Linux Primer: A practical, real-world  approach.

Cheers,

Ra=FAl Moreno



Ra=FAl Moreno Beltr=E1n
Telvent Energ=EDa, S. A.
Divisi=F3n de Tecnolog=EDa. Desarrollo Software
Tlfo: 954935670



"fabien boucher" <fabien.fb@gmail.com>
"fabien boucher"
Enviado por:
linuxppc-embedded-bounces+raul.moreno=3Dtelvent.abengoa.com@ozlabs.org
13/09/2007 16:05
                                                                       =
                                                
 Para:   linuxppc-embedded@ozlabs.org                                  =
                                                
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 cc:                                                                   =
                                                
                                                                       =
                                                
 Asunto: Informations about mem and proc environment between bootloader=
 and     kernel                                 
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And I need some help for my project (I'm in internship) to port linux o=
n a
custom board.
This board has been developped by the company where i'm doing the inter=
ship
and it's
based on a MPC875 with RAM and Flash chips and several other devices.
Currently the board run with a BSP developped
by the company's developpers, the BSP launch Psos.
This BSP is able to decompress an image and load it in RAM.
I plan to use U-boot to be more able to boot a kernel but as it's not a=

common
board so it's not initialy supported by U-boot. So I have two choices f=
irst
use the BSP with some changes to adapt it for loading the Linux kernel =
or
using U-boot.
I'm looking for informations about the memory and processor environment=

needed by linux to
boot properly for evaluate whether the use of a customize BSP is the
easiest way against
the port of a new board under U-boot. So if someone know where i can fo=
und
those informations
concerning the step between where the boot program have control of the =
cpu
and where Linux
take control.

Thank you,
Fabien
_______________________________________________
Linuxppc-embedded mailing list
Linuxppc-embedded@ozlabs.org
https://ozlabs.org/mailman/listinfo/linuxppc-embedded=

Re: Informations about mem and proc environment between bootloader and kernel

[Wolfgang Denk]

In message <OFD1DD4A9B.76E5C9ED-ONC1257355.004E8905-C1257355.004F16D9@abengoa.com> you wrote:
> 
> you should download the U-boot sources from sourceforge.net. There is a

No, you should NOT.

The stuff on sourceforge is obsolete and has ot been updated for AGES.
And the page clearly states so.

U-Boot lives in the git repository only. See
http://www.denx.de/wiki/UBoot for details.

Best regards,

Wolfgang Denk

-- 
DENX Software Engineering GmbH,     MD: Wolfgang Denk & Detlev Zundel
HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany
Phone: (+49)-8142-66989-10 Fax: (+49)-8142-66989-80 Email: wd@denx.de
Making files is easy under  the  UNIX  operating  system.  Therefore,
users  tend  to  create  numerous  files  using large amounts of file
space. It has been said that the only standard thing about  all  UNIX
systems  is  the  message-of-the-day  telling users to clean up their
files.                             - System V.2 administrator's guide

DMA problem - mpc8xx

[raul.moreno]

Hi everybody,

I am having problems with the serial cpm driver in a mpc866. But I've f=
ound
out that my problem comes from the DMA and not really from the driver. =
 The
Rx and Tx buffers use the DMA and then the sytem hangs. However, if I s=
et
these buffers to internal ram memory (DPRAM), it works. The DMA address=
 is
configured with a kernel parameter in advance setup:
CONFIG_CONSISTENT_START (and the size in CONFIG_CONSISTENT_SIZE), but I=

don't know what they are exactly and I could not find a right documenta=
tion
about it.
I saw a pair of mailing list where some guys set the
CONFIG_CONSISTENT_START to 0xff100000, but my driver continues failing =
(and
an error about dma-mapping appears in the boot).

Did anyone have a similar problem?
Could anyone help me?

Thanks in advance,

Ra=FAl Moreno=

Re: DMA problem - mpc8xx

[Scott Wood]

raul.moreno@telvent.abengoa.com wrote:
> Hi everybody,
> 
> I am having problems with the serial cpm driver in a mpc866. But I've found
> out that my problem comes from the DMA and not really from the driver.  The
> Rx and Tx buffers use the DMA and then the sytem hangs. However, if I set
> these buffers to internal ram memory (DPRAM), it works. The DMA address is
> configured with a kernel parameter in advance setup:
> CONFIG_CONSISTENT_START (and the size in CONFIG_CONSISTENT_SIZE), but I
> don't know what they are exactly and I could not find a right documentation
> about it.
> I saw a pair of mailing list where some guys set the
> CONFIG_CONSISTENT_START to 0xff100000, but my driver continues failing (and
> an error about dma-mapping appears in the boot).

What kernel version?  arch/ppc or arch/powerpc?  What is the error about 
dma-mapping that you get?  What does your memory map look like (in 
particular, is there anything that might be getting mapped in conflict 
with the consistent area at 0xff100000)?

-Scott