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[Qemu-devel] Re: Re: [PATCH 0/4] ppc: Fix PReP emulation


From: François Revol
Subject: [Qemu-devel] Re: Re: [PATCH 0/4] ppc: Fix PReP emulation
Date: Mon, 20 Dec 2010 13:19:52 +0100

>>> So we certainly do need some open source firmware solution for prep to at 
>>> least have Linux running. For other guests, I don't see a reason why users 
>>> shouldn't try to fetch a real firmware blob separately :).
>> 
>> We're not shipping any firmware for ppcemb either, so that argument seems 
>> moot. OpenBIOS, SeaBIOS and ZIPL are the only ones currently. Feel free to 
>> supply additional blobs for U-Boot etc.
> 
> IIUC you don't need u-boot for the embedded targets. You just pass in a 
> kernel and the rest is magic.

This holds only for Linux which imposes its own startup API to bootloaders and 
go with kernel drivers directly.

Other OS like Haiku use a 2nd stage bootloader which assumes a working callable 
BIOS (OF on ppc), and getting it to run on U-Boot is already tricky on its own.

>> Recent vanilla Linux kernels wouldn't run on PReP. So what Linux do you want 
>> to run using open source firmware?
>> I certainly do not intend to write firmware for the upcoming 40p machine. If 
>> Linux runs on real 40p hardware then it should run with real firmware under 
>> emulation, too. QEMU is an emulation project, not a Linux testing framework.
> 
> I completely agree. Linux is usually easy because it's fully open source and 
> supports a lot of targets. If you feel like running NetBSD or Haiku instead, 
> feel free to do so.

Thanks for thinking about Haiku ;)

Btw there are other existing targets, like AROS, MorphOS, or AmigaOS which uses 
a modified U-Boot with a 'boota' command that passes their 2nd stage Parthenope 
bootloader a list of BIOS-like callbacks into U-Boot, cf. :
http://www.acube-systems.biz/index.php?page=hardware&pid=2
http://www.acube-systems.biz/download/u-boot-1.3.1c_20101206_prod.tar.gz

Though they probably won't run on PReP, and PReP support in Haiku might come 
only for the sake of supporting the BeBox, which had its own dumb firmware 
(MAME seems to have some emulation support for BeBox).

OTOH, I've been thinking about adding a Sam440 target, but it'd still require 
the custom U-Boot to start AmigaOS for example.

François.


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