Re: [Qemu-devel] [PATCH 27/27] Add SLOF-based partition firmware for pSeries machine, allowing more boot options

[Anthony Liguori <anthony@codemonkey.ws>]

On 03/24/2011 10:21 PM, David Gibson wrote:
> Currently, the emulated pSeries machine requires the use of the
> -kernel parameter in order to explicitly load a guest kernel.  This
> means booting from the virtual disk, cdrom or network is not possible.
>
> This patch addresses this limitation by inserting a within-partition
> firmware image (derived from the "SLOF" free Open Firmware project).
> If -kernel is not specified, qemu will now load the SLOF image, which
> has access to the qemu boot device list through the device tree, and
> can boot from any of the usual virtual devices.
>
> In order to support the new firmware, an extension to the emulated
> machine/hypervisor is necessary.  Unlike Linux, which expects
> multi-CPU entry to be handled kexec() style, the SLOF firmware expects
> only one CPU to be active at entry, and to use a hypervisor RTAS
> method to enable the other CPUs one by one.
>
> This patch also implements this 'start-cpu' method, so that SLOF can
> start the secondary CPUs and marshal them into the kexec() holding
> pattern ready for entry into the guest OS.  Linux should, and in the
> future might directly use the start-cpu method to enable initially
> disabled CPUs, but for now it does require kexec() entry.
>
> Signed-off-by: Benjamin Herrenschmidt<benh@kernel.crashing.org>
> Signed-off-by: Paul Mackerras<paulus@samba.org>
> Signed-off-by: David Gibson<dwg@au1.ibm.com>

We should pull in SLOF via a git submodule.  That ensures we ship the 
source code along with the binary.

Regards,

Anthony Liguori