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From: Gerd Hoffmann <kraxel@redhat.com>
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Subject: Re: [Qemu-devel] [PATCH] turn firmware image filename into a
	machine option
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To: Peter Maydell <peter.maydell@linaro.org>
Cc: Mark Langsdorf <mark.langsdorf@calxeda.com>, QEMU Developers <qemu-devel@nongnu.org>, Fabien Chouteau <chouteau@adacore.com>, Alexander Graf <agraf@suse.de>, Blue Swirl <blauwirbel@gmail.com>, Michael Walle <michael@walle.cc>, =?ISO-8859-1?Q?Herv=E9?= Poussineau <hpoussin@reactos.org>, Paul Brook <paul@codesourcery.com>, Anthony Liguori <anthony@codemonkey.ws>, "open
	list:New World" <qemu-ppc@nongnu.org>, Andreas =?ISO-8859-1?Q?F=E4rber?= <andreas.faerber@web.de>, Aurelien Jarno <aurelien@aurel32.net>, Richard Henderson <rth@twiddle.net>

  Hi,

> -bios we're stuck with because it's a legacy
> option,

What is legacy about it?

Well, the x86-centric name of course.  Thats why the machine option is
named 'firmware' instead.

It also doesn't use QemuOpts, which is fixed by this patch.

Anything else?

> >> Why is this a machine option rather than a property of
> >> the ROM/flash device?
> >
> > Not all machines have a flash device.
> 
> No, but they must have *something* that the firmware code lives in...

Some don't.  They just memcpy the firmware into guest ram instead.

Most have a memory region for the firmware which gets mapped into guest
address space.  Sometimes pulled out of thin air, sometimes modeled as
proper device.

> > Also flash drives don't want a
> > simple (readonly) image file but a (writable) blockdev as backing
> > storage, at least the pflash device emulation I've briefly looked at.
> 
> ...so how does this work for machines where the firmware lives in
> a flash device?

pc: In case '-pflash $blockdev' is present '-bios $image' is ignored.

My patch doesn't change that behavior, i.e. -machine firmware=$image is
ignored too in case -plflash is present on the command line.

Given that pflash operates on a blockdev I don't see a obvious way to
change that ...

cheers,
  Gerd