Re: booting Linux 2.6.15 using a ramdisk and greater than 512MB of DRAM

Dear Scott,

in message [ref] you wrote:

I am not sure if this is a linux question or a u-boot question.  I have
a custom MPC8540 board running U-boot 1.1.4.  With a NFS root
configuration, I have booted and run 2.6.15 with memory from 256MB to
2GB.  If I build a ramdisk image (or even if I use the ramdisk image
with the 85xx version of ELDK 4.0) and then combine it with the kernel
image (vmlinux.gz) using "mkimage", the linux boot blows out with an
oops if I boot the board with more that 512MB of DRAM.  From the U-boot

Do you see something like

	mem_pieces_remove: [3fe32000,3ff93ec7) not in any region

in your boot messages?

output, it looks like the ramdisk image is getting copied to the upper
portion of DRAM.  Is it possible that the kernel doesn't map enough DRAM
to allow the image to be read?

I haven't spent a lot of time debugging this once I saw that the 512MB
configuration worked OK.  Has anyone run into this?

Yes. Normally you can use only use 0x30000000 (768MB)  RAM  (lowmem);
if  you  need  more  you  have  to  change your kernel configuration,
including shifting the kernel start address.

For example, on on a 1 GB system something like this could work:

	CONFIG_ADVANCED_OPTIONS=y
	CONFIG_LOWMEM_SIZE_BOOL=y
	CONFIG_LOWMEM_SIZE=0x40000000
	CONFIG_KERNEL_START_BOOL=y
	CONFIG_KERNEL_START=0xa0000000
	# CONFIG_CONSISTENT_START_BOOL is not set
	# CONFIG_CONSISTENT_SIZE_BOOL is not set
	# CONFIG_BOOT_LOAD_BOOL is not set


Best regards,

Wolfgang Denk

-- 
Software Engineering:  Embedded and Realtime Systems,  Embedded Linux
Phone: (+49)-8142-66989-10 Fax: (+49)-8142-66989-80 Email: wd@denx.de
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