initramfs failing, 7MB limit?

Michael Neuling mikey at
Wed Mar 12 08:36:35 EDT 2008

> This is OT but I'm seeing what seems like a 7MB limit on an initramfs 
> under
> I can boot an initramfs which also works under kexec that has a cpio 
> size of 6480384 bytes.  I have another (created the same way) that 
> has more userland tools with a size of 7395328 bytes. That fails 
> under both boot and kexec with the kernel not finding "/init" and 
> panicking. "/init"  is present and executable in the initramfs. This 
> fails on the target hardware and two other standard PC hardware with 
> 256M, 512M and 1G of RAM.
> I use the kernel scripts (scripts/  and 
> usr/gen_init_cpio ) to create the cpio based initramfs but it's not 
> embedded in the kernel. It's a standalone initramfs that gets passed 
> to the bootloader/kexec.
> It's my understanding that with an initramfs, one is just limited to 
> available RAM and there are no set size limits.
> Anyone else see this behavior or am I doing something incredibly stupid.

We have booted with very large initramfs (greater than 100MB) on ppc64
and not had a problem.  

You're probably having problems the initramfs overwriting some other
important information.  What does the memory map look like?  Where is
the initramfs located in memory and what is after it?


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