x86: Unplug emulated disks and nics.

Add a xen_emul_unplug command line option to the kernel to unplug
xen emulated disks and nics.

Set the default value of xen_emul_unplug depending on whether or
not the Xen PV frontends and the Xen platform PCI driver have
been compiled for this kernel (modules or built-in are both OK).

The user can specify xen_emul_unplug=ignore to enable PV drivers on HVM
even if the host platform doesn't support unplug.

Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>

1 files changed, 11 insertions, 0 deletions

diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index 82d6aeb5228f..eefcd805102e 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -115,6 +115,7 @@ parameter is applicable:
                         More X86-64 boot options can be found in
                         Documentation/x86/x86_64/boot-options.txt .
         X86     Either 32bit or 64bit x86 (same as X86-32+X86-64)
+        XEN     Xen support is enabled
 
 In addition, the following text indicates that the option:
 
@@ -2879,6 +2880,16 @@ and is between 256 and 4096 characters. It is defined in the file
         xd=             [HW,XT] Original XT pre-IDE (RLL encoded) disks.
         xd_geo=         See header of drivers/block/xd.c.
 
+        xen_emul_unplug=                [HW,X86,XEN]
+                        Unplug Xen emulated devices
+                        Format: [unplug0,][unplug1]
+                        ide-disks -- unplug primary master IDE devices
+                        aux-ide-disks -- unplug non-primary-master IDE devices
+                        nics -- unplug network devices
+                        all -- unplug all emulated devices (NICs and IDE disks)
+                        ignore -- continue loading the Xen platform PCI driver even
+                                if the version check failed
+
         xirc2ps_cs=     [NET,PCMCIA]
                         Format:
                         <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]