[Xen-changelog] [xen-unstable] Update for vtd.txt: add VT-d hotplug description, remove MSI

[Xen patchbot-unstable <patchbot-unstable@xxxxxxxxxxxxxxxxxxx>]

# HG changeset patch
# User Keir Fraser <keir.fraser@xxxxxxxxxx>
# Date 1210148609 -3600
# Node ID a3b8a99c26ebb464a3c9791a5d48e1bf90c800b8
# Parent  2cc926c18a7bb7f2a720c15054a4f4ac5249dc35
Update for vtd.txt: add VT-d hotplug description, remove MSI
limitation note because Xen has supported MSI, and add link of VT-d
howto on xen wiki for more information about VT-d enabled systems.

Signed-off-by: Weidong Han <weidong.han@xxxxxxxxx>
Signed-off-by: Edwin Zhai <edwin.zhai@xxxxxxxxx>
---
 docs/misc/vtd.txt |   35 +++++++++++++++++++++++++++++++----
 1 files changed, 31 insertions(+), 4 deletions(-)

diff -r 2cc926c18a7b -r a3b8a99c26eb docs/misc/vtd.txt
--- a/docs/misc/vtd.txt Wed May 07 09:22:05 2008 +0100
+++ b/docs/misc/vtd.txt Wed May 07 09:23:29 2008 +0100
@@ -2,7 +2,7 @@ Authors : Allen Kay    <allen.m.kay@inte
 Authors : Allen Kay    <allen.m.kay@xxxxxxxxx>
           Weidong Han  <weidong.han@xxxxxxxxx>
 Created : October-24-2007
-Updated : December-13-2007
+Updated : May-07-2007
 
 How to turn on VT-d in Xen
 --------------------------
@@ -22,7 +22,7 @@ title Xen-Fedora Core (2.6.18-xen)
 title Xen-Fedora Core (2.6.18-xen)
         root (hd0,0)
         kernel /boot/xen.gz com1=115200,8n1 console=com1
-        module /boot/vmlinuz-2.6.18.8-xen root=LABEL=/ ro console=tty0 
console=ttyS0,115200,8n1 pciback.hide=(01:00.0)(03:00.0) 
pciback.verbose_request=1 apic=debug
+        module /boot/vmlinuz-2.6.18.8-xen root=LABEL=/ ro xencons=ttyS 
console=tty0 console=ttyS0, pciback.hide=(01:00.0)(03:00.0)
         module /boot/initrd-2.6.18-xen.img
 
 12) reboot system
@@ -47,14 +47,39 @@ 1) Host OS: PAE, 64-bit
 1) Host OS: PAE, 64-bit
 2) Guest OS: 32-bit, PAE, 64-bit
 
-Because current Xen doesn't support MSI, for guest OS which uses MSI by 
default, need to add "pci=nomsi" option on its grub, e.g. RHEL5, FC6.
-
 
 Combinations Tested:
 --------------------
 
 1) 64-bit host: 32/PAE/64 Linux/XP/Win2003/Vista guests
 2) PAE host: 32/PAE Linux/XP/Win2003/Vista guests
+
+
+VTd device hotplug:
+-------------------
+ 
+2 virtual PCI slots (6~7) are reserved in HVM guest to support VTd hotplug. If 
you have more VTd devices, only 2 of them can support hotplug. Usage is simple:
+
+ 1. List the VTd device by dom. You can see a VTd device 0:2:0.0 is inserted 
in the HVM domain's PCI slot 6. '''lspci''' inside the guest should see the 
same.
+
+       [root@vt-vtd ~]# xm pci-list HVMDomainVtd
+       VSlt domain   bus   slot   func
+       0x6    0x0  0x02   0x00    0x0
+
+ 2. Detach the device from the guest by the physical BDF. Then HVM guest will 
receive a virtual PCI hot removal event to detach the physical device
+
+       [root@vt-vtd ~]# xm pci-detach HVMDomainVtd 0:2:0.0
+
+ 3. Attach a PCI device to the guest by the physical BDF and desired virtual 
slot(optional). Following command would insert the physical device into guest's 
virtual slot 7
+
+       [root@vt-vtd ~]# xm pci-attach HVMDomainVtd 0:2:0.0 7
+
+VTd hotplug usage model:
+------------------------
+
+ * For live migration: As you know, VTd device would break the live migration 
as physical device can't be save/restored like virtual device. With hotplug, 
live migration is back again. Just hot remove all the VTd devices before live 
migration and hot add new VTd devices on target machine after live migration.
+
+ * VTd hotplug for device switch: VTd hotplug can be used to dynamically 
switch physical device between different HVM guest without shutdown.
 
 
 VT-d Enabled Systems
@@ -74,3 +99,5 @@ http://www.dell.com/content/products/cat
 - HP Compaq:  DC7800
 
http://h10010.www1.hp.com/wwpc/us/en/en/WF04a/12454-12454-64287-321860-3328898.html
 
+For more information, pls refer to http://wiki.xensource.com/xenwiki/VTdHowTo.
+

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