Re: [Qemu-devel] alpha platform is missing files after initrd load

[Richard Henderson <rth@twiddle.net>]

On 11/04/2016 05:08 AM, Stefan Hajnoczi wrote:
> On Thu, Oct 20, 2016 at 12:45:37PM +0200, Dennis Luehring wrote:
>> qemu: 2.7.x (git head)
>> platform: Alpha (Clipper)
>
> Two options:
>
> 1. Not many people use Alpha.  You may need to debug this yourself by
>    learning about the Linux alpha boot protocol (where the initramfs is
>    loaded and how big that region of memory may be).  Then you can
>    verify the memory contents after QEMU has loaded the
>    kernel/initramfs using monitor commands to read memory.  You may need
>    to look at QEMU's kernel/initramfs loading code to see what it's
>    doing.
>
> 2. If it worked in a previous QEMU version, please use git-bisect(1) to
>    find out which commit broke it.
>
> Good luck!

We debugged this via private mail.

For the 4.7 kernel, we had enough ram to unpack the (large) initrd; with the 
4.8 kernel, we ran out.  The 4.8 kernel did in fact print an (obscure) error 
message to that effect, which had not been noticed.  I consider it a bug that 
the kernel does not treat this like any other failure to mount /root, via panic.

Increasing ram from 1GB to 2GB allowed the 4.8 kernel to succeed in unpacking 
and booting off of the initrd.


r~