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From: Anthony Liguori <anthony@codemonkey.ws>
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Date: Thu, 13 Jun 2013 19:59:37 -0500
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Subject: Re: [Qemu-devel] [PATCH] qemu: piix: PCI bridge ACPI hotplug support
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To: Paolo Bonzini <pbonzini@redhat.com>, "Michael S. Tsirkin" <mst@redhat.com>
Cc: Peter Maydell <peter.maydell@linaro.org>, Jordan Justen <jljusten@gmail.com>, seabios@seabios.org, qemu-devel <qemu-devel@nongnu.org>, Laszlo Ersek <lersek@redhat.com>, Kevin O'Connor <kevin@koconnor.net>, Gerd Hoffmann <kraxel@redhat.com>, David Woodhouse <dwmw2@infradead.org>

Paolo Bonzini <pbonzini@redhat.com> writes:

> Il 11/06/2013 03:35, Michael S. Tsirkin ha scritto:
>> Two points
>> 1. You never explained what you mean by un-hardware like.
>> 
>>    Currently bios is in a ROM device, and it has a
>>    template for ACPI tables together with it.
>>    This simply moves the tables to a separate ROM
>>    device (FW CFG), and generalizes the template using
>>    the linker interface.
>>    One ROM is hardware-like but two is un-hardware like?
>> 
>>    ACPI tables are static so it's likely lots of
>>    hardware has at least some of them pre-formatted in flash,
>>    then tweak some things like SRAT a bit.
>
> Also having a "bootstrap processor" was certainly not unheard of some
> decades ago.  Right now we get all sort of SMM hacks instead of adding
> more processors, but it's certainly not un-hardware like.

It's still not unheard of.  This is how power systems work still.

However, with PCs, the ACPI tables are generated by/included in the
firmware.  There's no question about that.

>
> Maybe we should just have a bytecode interpreter and write the ACPI
> generator in that language. :)

Indeed, we can even using an existing bytecode like the x86 instruction
set and use this VM called KVM to execute it.  I hear there are even C
compilers for this bytecode ;-)

Regards,

Anthony Liguori

> Paolo