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linux/drivers/xen/Kconfig
Stefano Stabellini 183d03cc4f xen: Xen PCI platform device driver.
Add the xen pci platform device driver that is responsible
for initializing the grant table and xenbus in PV on HVM mode.
Few changes to xenbus and grant table are necessary to allow the delayed
initialization in HVM mode.
Grant table needs few additional modifications to work in HVM mode.

The Xen PCI platform device raises an irq every time an event has been
delivered to us. However these interrupts are only delivered to vcpu 0.
The Xen PCI platform interrupt handler calls xen_hvm_evtchn_do_upcall
that is a little wrapper around __xen_evtchn_do_upcall, the traditional
Xen upcall handler, the very same used with traditional PV guests.

When running on HVM the event channel upcall is never called while in
progress because it is a normal Linux irq handler (and we cannot switch
the irq chip wholesale to the Xen PV ones as we are running QEMU and
might have passed in PCI devices), therefore we cannot be sure that
evtchn_upcall_pending is 0 when returning.
For this reason if evtchn_upcall_pending is set by Xen we need to loop
again on the event channels set pending otherwise we might loose some
event channel deliveries.

Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Signed-off-by: Sheng Yang <sheng@linux.intel.com>
Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
2010-07-22 16:46:09 -07:00

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menu "Xen driver support"
depends on XEN
config XEN_BALLOON
bool "Xen memory balloon driver"
default y
help
The balloon driver allows the Xen domain to request more memory from
the system to expand the domain's memory allocation, or alternatively
return unneeded memory to the system.
config XEN_SCRUB_PAGES
bool "Scrub pages before returning them to system"
depends on XEN_BALLOON
default y
help
Scrub pages before returning them to the system for reuse by
other domains. This makes sure that any confidential data
is not accidentally visible to other domains. Is it more
secure, but slightly less efficient.
If in doubt, say yes.
config XEN_DEV_EVTCHN
tristate "Xen /dev/xen/evtchn device"
default y
help
The evtchn driver allows a userspace process to triger event
channels and to receive notification of an event channel
firing.
If in doubt, say yes.
config XENFS
tristate "Xen filesystem"
default y
help
The xen filesystem provides a way for domains to share
information with each other and with the hypervisor.
For example, by reading and writing the "xenbus" file, guests
may pass arbitrary information to the initial domain.
If in doubt, say yes.
config XEN_COMPAT_XENFS
bool "Create compatibility mount point /proc/xen"
depends on XENFS
default y
help
The old xenstore userspace tools expect to find "xenbus"
under /proc/xen, but "xenbus" is now found at the root of the
xenfs filesystem. Selecting this causes the kernel to create
the compatibility mount point /proc/xen if it is running on
a xen platform.
If in doubt, say yes.
config XEN_SYS_HYPERVISOR
bool "Create xen entries under /sys/hypervisor"
depends on SYSFS
select SYS_HYPERVISOR
default y
help
Create entries under /sys/hypervisor describing the Xen
hypervisor environment. When running native or in another
virtual environment, /sys/hypervisor will still be present,
but will have no xen contents.
config XEN_PLATFORM_PCI
tristate "xen platform pci device driver"
depends on XEN
default m
help
Driver for the Xen PCI Platform device: it is responsible for
initializing xenbus and grant_table when running in a Xen HVM
domain. As a consequence this driver is required to run any Xen PV
frontend on Xen HVM.
endmenu