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Re: [Qemu-devel] [Qemu-ppc] [PATCH 0/9] PPC: e500: Use u-boot as firmwar

From: Alexander Graf
Subject: Re: [Qemu-devel] [Qemu-ppc] [PATCH 0/9] PPC: e500: Use u-boot as firmware
Date: Thu, 15 May 2014 18:38:12 +0200
User-agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.9; rv:24.0) Gecko/20100101 Thunderbird/24.5.0

On 15.05.14 18:32, Alexander Graf wrote:
Today we don't run any firmware on our e500 platform. You're either running
a Linux kernel directly through -kernel or you don't boot the VM at all.

This is bad for multiple reasons. The normal firmware on e500 based systems
is u-boot. Some OSes (IIRC FreeBSD) rely on u-boot for their 2nd stage boot
loader. Since that relies on interfaces u-boot provides we can't execute it

The other case where we're falling short of expectations that I'm aware of
is network boot. With a firmware you can actually pxe boot a virtual machine.

This patch set implements all the pieces necessary to run u-boot as the
firmware for our e500 platforms: mpc8544ds and e500plat. It is based on upstream
u-boot code that implements a target specific for the simplified system QEMU

Due to popular demand the default -kernel booting has *not* been changed from
directly booting into the kernel. This is possible because we don't need to run
firmware to provide run time services.

However, whenever the user explicitly defines a -bios blob, we run it.
That means if you want to route a -kernel boot through u-boot you have to pass
in -bios pc-bios/u-boot.e500 -kernel uImage.

Please try out as many things as you're able to try.

Known missing bits:

   - -boot doesn't get interpreted yet
   - pflash is missing, so the environment is volatile
   - no block drivers available (ata_piix is broken in u-boot and virtio-blk
     is missing)
   - KVM patches to support u-boot are probably going to hit 3.16

This is v2 of the patch set.

v1 -> v2:

  - correct permission access to USER_RO
  - Update to newer u-boot version
  - Add git submodule for u-boot
  - skip u-boot when -kernel and no -bios are given


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