[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: [Qemu-devel] [PATCH] qemu: piix: PCI bridge ACPI hotplug support
From: |
Gerd Hoffmann |
Subject: |
Re: [Qemu-devel] [PATCH] qemu: piix: PCI bridge ACPI hotplug support |
Date: |
Tue, 11 Jun 2013 09:42:29 +0200 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/20130513 Thunderbird/17.0.6 |
Hi,
>>> Portability:
>>> - Non x86 (or any Linux) platforms don't need any of this code.
>>> They can keep happily using SHPC the way
>>> they always did.
>>
>> Hmm. Is is possible to write a SHPC driver in AML? I think it would be
>> alot better to have one guest/host interface for pci bridge hotplug
>> instead of two.
>>
>> cheers,
>> Gerd
>
> No, it's not possible, SHPC is not designed to be used from ACPI.
>
> Two reasons off the top of my head, there are likely others:
>
> 1. SHPC uses regular PCI interrupts to signal events. It does not signal
> GFE and SCI.
>
> 2. SHPC uses config accesses to get information from device.
> ACPI does not allow config access anywhere except the root bus from ACPI
> (This requirement is designed to give the OS freedom
> to reconfigure PCI in an arbitrary way).
OK, so it's designed for OSes to have native SHPC support. Linux has that?
Quick googling found me Windows Vista+ has it too, correct? So that
leaves Win2k + WinXP versions. Older Windows versions do not support
pci hotplug at all. Win2k is EOL already. WinXP will follow soon.
More users?
/me wonders whenever it is worth hopping through the loops needed to
support ACPI-based hotplug of devices behind bridges in the first place.
cheers,
Gerd
Re: [Qemu-devel] [PATCH] qemu: piix: PCI bridge ACPI hotplug support, Michael S. Tsirkin, 2013/06/11
Re: [Qemu-devel] [PATCH] qemu: piix: PCI bridge ACPI hotplug support, Gerd Hoffmann, 2013/06/11