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Re: [Xen-devel] [PATCH 0/3] RFC: PCIe IO space multiplexing for bootable

To: Isaku Yamahata <yamahata@xxxxxxxxxxxxx>
Subject: Re: [Xen-devel] [PATCH 0/3] RFC: PCIe IO space multiplexing for bootable pass through HVM domain
From: Yuji Shimada <shimada-yxb@xxxxxxxxxxxxxxx>
Date: Thu, 02 Apr 2009 16:12:56 +0900
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On Thu, 2 Apr 2009 13:01:28 +0900
Isaku Yamahata <yamahata@xxxxxxxxxxxxx> wrote:

> Hi all. This is for PCIe IO space multiplexing. Please comment.
> It is not uncommon that a big iron for server consolidation has
> many (e.g. > 16) PCIe slots. It will hold many domains, and
> the administrator wants them to boot from pass through devices.
> But currently up to 16 hvm domains can boot from pass through device.
> This patch series addresses this issue by multiplexing IO space access.
> The patches are composed of
>       Linux part: IO space ressignment code and multiplexing driver
>       xen part:   udev script for the driver
>       ioemu part: make use of the PCIe io space multiplexing driver
> Usage:
> Add dom0 kernel command line specifying the pass through devices by
>   guestiomuldev=[<segment>:]<bus>:<dev>[,[<segment:><bus>:dev]][,...]
> (Don't forget add related options. pciback.hide, reassign_resources,
> reassigndev or guestdev.)

It is nice to add "iomul" flag to "guestdev=" boot parameter, because
segment# and bus# can be changed on rebooting. In addition to this,
specifying pciback.hide, reassigndev and guestioemuldev is redundant.

This is a example.


Incidentally, I will submit the patch to use device path to assign
devices to guest domain as discussed in xen-devel, after xen 3.4 is

Yuji Shimada

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