How to use ramdisk on the ml300?

      If i want use ramdisk on the ml300 , i must use u-boot in my system ?
     many thanks

Yanlong,

As I discovered today, it is not necessary to use u-boot on the ml507 =
board.  I cannot speak with certainty about the ml300.  For the ml507 =
the ramdisk image gets saved as a separate section in the elf file that =
is downloaded with the zImage.  In the ml507 case the image is a gzipped =
ext2 filesystem.  Makes a very tidy package I'm sure you will agree!=20

Stu



-----Original Message-----
From: <redacted> on =
behalf of yanlong wang
Sent: Wed 8/13/2008 8:08 PM
To: <redacted>
Subject: How to use ramdisk on the ml300?
=20
      If i want use ramdisk on the ml300 , i must use u-boot in my =
system ?
     many thanks
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Hi,

As I discovered today, it is not necessary to use u-boot on the ml507
board.  I cannot speak with certainty about the ml300.  For the ml507
the ramdisk image gets saved as a separate section in the elf file
that is downloaded with the zImage.  In the ml507 case the image is a
gzipped ext2 filesystem.  Makes a very tidy package I'm sure you will
agree!

But with U-boot it can be way more comfortable!

Regards,
Ph :)

-- 
http://www.hachti.de

 I use the make zImage.initrd to build my linux and i creat a
ramdisk file ,set the console root=/dev/ram.
  next i download the zImage.initrd.elf to the board,and down load
the ramdisk file to the right place , but  in the boot message , it
not try to load the ramdisk as rootfiles , it really boring me ,why?
  Thanks for your help
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Hi Yanlong,

On Thu, Aug 14, 2008 at 5:08 AM, yanlong wang [off-list ref] wrote:

     If i want use ramdisk on the ml300 , i must use u-boot in my system ?
    many thanks

I suppose you want to use an initial ram filesystem as
rootfs to boot your system?

You have to point CONFIG_INITRAMFS_SOURCE="" to a cpio
archive or a directory which contains your rootfs. If
you use a directory structure then you should set your
uid/gid to make the build process convert the owner
to root:

# if your uid/gid is 500:
CONFIG_INITRAMFS_ROOT_UID=500
CONFIG_INITRAMFS_ROOT_GID=500

Don't forget to set CONFIG_BLK_DEV_RAM=y to be able
to use a ramdisk at all.

I'm also using the ml300 board and I create my kernel
with: make simpleImage.virtex405-ml300

My dts is arch/powerpc/boot/dts/virtex405-ml300.dts.
There is no kernel boot command line needed to use
the initramfs in my case (I only set up my console
to the uart). Just download the image
arch/powerpc/boot/simpleImage.virtex405-ml300.elf
with xmd to your ml300 and run it.

I hope this works for you.

Regards
Jens

Hi JensWirth,
    Thanks  for your reply :). I have some questions here.
    (1)You told me "make simpleImage.virtex405-ml300",i only know "make
zImage" and "make zImage.initrd" ,what it is this command mean???
    (2)What is dts ? I don't know what is this :(
Regards,
YanLong:)

  

Jens Wirth wrote:

Hi Yanlong,

On Thu, Aug 14, 2008 at 5:08 AM, yanlong wang [off-list ref]
wrote:

quoted

     If i want use ramdisk on the ml300 , i must use u-boot in my system
?
    many thanks

I suppose you want to use an initial ram filesystem as
rootfs to boot your system?

You have to point CONFIG_INITRAMFS_SOURCE="" to a cpio
archive or a directory which contains your rootfs. If
you use a directory structure then you should set your
uid/gid to make the build process convert the owner
to root:

# if your uid/gid is 500:
CONFIG_INITRAMFS_ROOT_UID=500
CONFIG_INITRAMFS_ROOT_GID=500

Don't forget to set CONFIG_BLK_DEV_RAM=y to be able
to use a ramdisk at all.

I'm also using the ml300 board and I create my kernel
with: make simpleImage.virtex405-ml300

My dts is arch/powerpc/boot/dts/virtex405-ml300.dts.
There is no kernel boot command line needed to use
the initramfs in my case (I only set up my console
to the uart). Just download the image
arch/powerpc/boot/simpleImage.virtex405-ml300.elf
with xmd to your ml300 and run it.

I hope this works for you.

Regards
Jens
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5 more quoted lines

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Hi

On Thu, Aug 14, 2008 at 12:44 PM, wangyanlong [off-list ref] wrote:

Hi JensWirth,
   Thanks  for your reply :). I have some questions here.
   (1)You told me "make simpleImage.virtex405-ml300",i only know "make
zImage" and "make zImage.initrd" ,what it is this command mean???

It's a relatively new target in the arch/powerpc/boot/Makefile which
wraps your compressed kernel and bootcode together with a device tree
blob. A device tree blob is created using a device tree source (dts).

   (2)What is dts ? I don't know what is this :(

A device tree source is plain text. Look inside arch/powerpc/boot/dts.
A device tree is essential if you want to boot an ARCH=powerpc
Linux-Kernel. Read this:
http://ols.fedoraproject.org/OLS/Reprints-2008/likely2-reprint.pdf

I supposed you were using 2.6.26 or 2.6.27-rcX

Regards
Jens

It is work now ,Thanks for all your help :)

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