Re: RAMDisk Blues

From: Nick DeClario (
Date: Tue Jul 17 2001 - 13:57:30 EST

Hi, I know there is this option in the kernel:

Default RAM disk size
  The default value is 4096. Only change this if you know what are
  you doing. If you are using IBM S/390, then set this to 8192.

I grabbed that from ~/linux/Documentation/ I have never
gone about changing this before as the largest RAM disks I have delt
with were no larger than 3Mb. But it defaults to 4Mb, so perhaps
increasing this would solve your problem.


Ivan Passos wrote:
> Hello,
> I'm trying to boot a Linux system that has the following configuration:
> - 32MB of Flash (IDE Flash Drive), where a kernel image and a compressed
> root filesystem image are stored.
> - 256MB of RAM, 128MB of which will be used as a RAMDisk (believe me, this
> is cheaper than 128MB Flash + 128MB RAM ... :).
> After looking for information on how to do that on the 'Net and in the
> Documentation/ directory of the kernel src, I've been able make the Flash
> Drive bootable. Unfortunately, it's bootable, but it doesn't boot
> successfully ... :(
> What I tried:
> - Compressed the image I used to boot the system from a regular IDE HD to
> a file called rd_image.gz (~20MB compressed), and copied it to the IDE
> Flash Drive.
> - Compiled a 2.4.6 kernel with RAMDisk and initrd support built-in, and
> then copied it to the IDE Flash Drive.
> - Ran LILO with the following config. file (based on the doc. I found so
> far):
> boot=/dev/hda # The FlashDrive device
> install=/boot/boot.b
> map=/boot/map
> append="ramdisk_size=131072 initrd=rd_image.gz"
> vga=normal
> default=Linux
> delay=5
> image=/boot/vmlinuz
> initrd=/boot/rd_image.gz
> root=/dev/ram0
> label=Linux
> read-only
> LILO completes the operation without problems (no errors). However, when I
> boot the system from the FlashDrive, this is the output I get:
> LILO Loading Linux ......................................................
> ..............................................
> That's it!! The system hangs at this point (it really hangs, to the point
> that the "soft" power on/off doesn't work anymore, and I have to turn off
> the system from the back in order to reboot it).
> What am I doing wrong?? Is my RAMDisk image too big (I thought there was
> no limit, as long as you had enough RAM ...)?? Does anyone here know a
> good resource on the 'Net where I can find more detailed information about
> creating a RAMDisk-based Linux system that boots from a device other than
> a floppy disk?? Most of the docs I found were related to boot / rescue /
> utility floppies, so I don't know whether this is the right way to do it
> or not ...
> Any help would be appreciated.
> Later,
> Ivan
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Nicholas DeClario
Systems Engineer                            Guardian Digital, Inc.
(201) 934-9230                Pioneering.  Open Source.  Security.  
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