Nonlinear mappings are (AFAIKS) simply a virtual memory concept that encodes
the virtual address -> file offset differently from linear mappings.
->populate is a layering violation because the filesystem/pagecache code
should need to know anything about the virtual memory mapping. The hitch here
is that the ->nopage handler didn't pass down enough information (ie. pgoff).
But it is more logical to pass pgoff rather than have the ->nopage function
calculate it itself anyway (because that's a similar layering violation).
Having the populate handler install the pte itself is likewise a nasty thing
to be doing.
This patch introduces a new fault handler that replaces ->nopage and
->populate and (later) ->nopfn. Most of the old mechanism is still in place
so there is a lot of duplication and nice cleanups that can be removed if
everyone switches over.
The rationale for doing this in the first place is that nonlinear mappings are
subject to the pagefault vs invalidate/truncate race too, and it seemed stupid
to duplicate the synchronisation logic rather than just consolidate the two.
After this patch, MAP_NONBLOCK no longer sets up ptes for pages present in
pagecache. Seems like a fringe functionality anyway.
NOPAGE_REFAULT is removed. This should be implemented with ->fault, and no
users have hit mainline yet.
[akpm@linux-foundation.org: cleanup]
[randy.dunlap@oracle.com: doc. fixes for readahead]
[akpm@linux-foundation.org: build fix]
Signed-off-by: Nick Piggin <npiggin@suse.de>
Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
Cc: Mark Fasheh <mark.fasheh@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Fix the race between invalidate_inode_pages and do_no_page.
Andrea Arcangeli identified a subtle race between invalidation of pages from
pagecache with userspace mappings, and do_no_page.
The issue is that invalidation has to shoot down all mappings to the page,
before it can be discarded from the pagecache. Between shooting down ptes to
a particular page, and actually dropping the struct page from the pagecache,
do_no_page from any process might fault on that page and establish a new
mapping to the page just before it gets discarded from the pagecache.
The most common case where such invalidation is used is in file truncation.
This case was catered for by doing a sort of open-coded seqlock between the
file's i_size, and its truncate_count.
Truncation will decrease i_size, then increment truncate_count before
unmapping userspace pages; do_no_page will read truncate_count, then find the
page if it is within i_size, and then check truncate_count under the page
table lock and back out and retry if it had subsequently been changed (ptl
will serialise against unmapping, and ensure a potentially updated
truncate_count is actually visible).
Complexity and documentation issues aside, the locking protocol fails in the
case where we would like to invalidate pagecache inside i_size. do_no_page
can come in anytime and filemap_nopage is not aware of the invalidation in
progress (as it is when it is outside i_size). The end result is that
dangling (->mapping == NULL) pages that appear to be from a particular file
may be mapped into userspace with nonsense data. Valid mappings to the same
place will see a different page.
Andrea implemented two working fixes, one using a real seqlock, another using
a page->flags bit. He also proposed using the page lock in do_no_page, but
that was initially considered too heavyweight. However, it is not a global or
per-file lock, and the page cacheline is modified in do_no_page to increment
_count and _mapcount anyway, so a further modification should not be a large
performance hit. Scalability is not an issue.
This patch implements this latter approach. ->nopage implementations return
with the page locked if it is possible for their underlying file to be
invalidated (in that case, they must set a special vm_flags bit to indicate
so). do_no_page only unlocks the page after setting up the mapping
completely. invalidation is excluded because it holds the page lock during
invalidation of each page (and ensures that the page is not mapped while
holding the lock).
This also allows significant simplifications in do_no_page, because we have
the page locked in the right place in the pagecache from the start.
Signed-off-by: Nick Piggin <npiggin@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Create a new NetLabel KAPI interface, netlbl_enabled(), which reports on the
current runtime status of NetLabel based on the existing configuration. LSMs
that make use of NetLabel, i.e. SELinux, can use this new function to determine
if they should perform NetLabel access checks. This patch changes the
NetLabel/SELinux glue code such that SELinux only enforces NetLabel related
access checks when netlbl_enabled() returns true.
At present NetLabel is considered to be enabled when there is at least one
labeled protocol configuration present. The result is that by default NetLabel
is considered to be disabled, however, as soon as an administrator configured
a CIPSO DOI definition NetLabel is enabled and SELinux starts enforcing
NetLabel related access controls - including unlabeled packet controls.
This patch also tries to consolidate the multiple "#ifdef CONFIG_NETLABEL"
blocks into a single block to ease future review as recommended by Linus.
Signed-off-by: Paul Moore <paul.moore@hp.com>
Signed-off-by: James Morris <jmorris@namei.org>
Many filesystems need a ->page-mkwrite callout to correctly
set up pages that have been written to by mmap. This is especially
important when mmap is writing into holes as it allows filesystems
to correctly account for and allocate space before the mmap
write is allowed to proceed.
Protection against truncate races is provided by locking the page
and checking to see whether the page mapping is correct and whether
it is beyond EOF so we don't end up allowing allocations beyond
the current EOF or changing EOF as a result of a mmap write.
SGI-PV: 940392
SGI-Modid: 2.6.x-xfs-melb:linux:29146a
Signed-off-by: David Chinner <dgc@sgi.com>
Signed-off-by: Christoph Hellwig <hch@infradead.org>
Signed-off-by: Tim Shimmin <tes@sgi.com>
* 'for-linus' of git://linux-nfs.org/~bfields/linux:
locks: fix vfs_test_lock() comment
locks: make posix_test_lock() interface more consistent
nfs: disable leases over NFS
gfs2: stop giving out non-cluster-coherent leases
locks: export setlease to filesystems
locks: provide a file lease method enabling cluster-coherent leases
locks: rename lease functions to reflect locks.c conventions
locks: share more common lease code
locks: clean up lease_alloc()
locks: convert an -EINVAL return to a BUG
leases: minor break_lease() comment clarification
Since posix_test_lock(), like fcntl() and ->lock(), indicates absence or
presence of a conflict lock by setting fl_type to, respectively, F_UNLCK
or something other than F_UNLCK, the return value is no longer needed.
Signed-off-by: "J. Bruce Fields" <bfields@citi.umich.edu>
Currently leases are only kept locally, so there's no way for a distributed
filesystem to enforce them against multiple clients. We're particularly
interested in the case of nfsd exporting a cluster filesystem, in which
case nfsd needs cluster-coherent leases in order to implement delegations
correctly.
Also add some documentation.
Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>
We've been using the convention that vfs_foo is the function that calls
a filesystem-specific foo method if it exists, or falls back on a
generic method if it doesn't; thus vfs_foo is what is called when some
other part of the kernel (normally lockd or nfsd) wants to get a lock,
whereas foo is what filesystems call to use the underlying local
functionality as part of their lock implementation.
So rename setlease to vfs_setlease (which will call a
filesystem-specific setlease after a later patch) and __setlease to
setlease.
Also, vfs_setlease need only be GPL-exported as long as it's only needed
by lockd and nfsd.
Signed-off-by: "J. Bruce Fields" <bfields@citi.umich.edu>
This interface allows the ability to write the majority of a driver in
userspace with only a very small shell of a driver in the kernel itself.
It uses a char device and sysfs to interact with a userspace process to
process interrupts and control memory accesses.
See the docbook documentation for more details on how to use this
interface.
From: Hans J. Koch <hjk@linutronix.de>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Benedikt Spranger <b.spranger@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
This defines a dev_vdbg() call, which is enabled with -DVERBOSE_DEBUG.
When enabled, dev_vdbg() acts just like dev_dbg(). When disabled, it is a
NOP ... just like dev_dbg() without -DDEBUG. The specific code was moved
out of a USB patch, but lots of drivers have similar support.
That is, code can now be written to use an additional level of debug
output, selected at compile time. Many driver authors have found this
idiom to be very useful. A typical usage model is for "normal" debug
messages to focus on fault paths and not be very "chatty", so that those
messages can be left on during normal operation without much of a
performance or syslog load. On the other hand "verbose" messages would be
noisy enough that they wouldn't normally be enabled; they might even affect
timings enough to change system or driver behavior.
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
This patch (as933) removes the deprecated dpm_runtime_suspend() and
dpm_runtime_resume() routines from the PM core. The only user of
those routines is the PCMCIA ds driver; local replacements are added.
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
CC: Dominik Brodowski <linux@dominikbrodowski.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
This allows the uevent file to handle any type of uevent action to be
triggered by userspace instead of just the "add" uevent.
Signed-off-by: Kay Sievers <kay.sievers@vrfy.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Introduce API to dynamically register and unregister multicast groups.
Signed-off-by: Johannes Berg <johannes@sipsolutions.net>
Acked-by: Patrick McHardy <kaber@trash.net>
Acked-by: Jamal Hadi Salim <hadi@cyberus.ca>
Signed-off-by: David S. Miller <davem@davemloft.net>
Allow kicking listeners out of a multicast group when necessary
(for example if that group is going to be removed.)
Signed-off-by: Johannes Berg <johannes@sipsolutions.net>
Acked-by: Patrick McHardy <kaber@trash.net>
Acked-by: Jamal Hadi Salim <hadi@cyberus.ca>
Signed-off-by: David S. Miller <davem@davemloft.net>
Allow changing the number of groups for a netlink family
after it has been created, use RCU to protect the listeners
bitmap keeping netlink_has_listeners() lock-free.
Signed-off-by: Johannes Berg <johannes@sipsolutions.net>
Acked-by: Patrick McHardy <kaber@trash.net>
Acked-by: Jamal Hadi Salim <hadi@cyberus.ca>
Signed-off-by: David S. Miller <davem@davemloft.net>
The TSEC/eTSEC can detect the interface to the PHY automatically,
but it isn't able to detect whether the RGMII connection needs internal
delay. So we need to detect that change in the device tree, propagate
it to the platform data, and then check it if we're in RGMII. This fixes
a bug on the 8641D HPCN board where the Vitesse PHY doesn't use the delay
for RGMII.
Signed-off-by: Andy Fleming <afleming@freescale.com>
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/hskinnemoen/avr32-2.6:
[AVR32] Initialize phy_mask for both macb devices
[AVR32] Fix atomic_add_unless() and atomic_sub_unless()
[AVR32] Correct misspelled CONFIG_BLK_DEV_INITRD variable.
[AVR32] Fix build error in parse_tag_rdimg()
[AVR32] Don't wire up macb0 unless SW6 is in default position
[AVR32] Wire up SSC platform device 0 as TX on ATSTK1000 board
[AVR32] Add Atmel SSC driver platform device to AT32AP architecture
[AVR32] Remove optimization of unaligned word loads
[AVR32] Make STK1000 mux settings configurable
[AVR32] CPU frequency scaling for AT32AP
[AVR32] Split SM device into PM, RTC, WDT and EIC
[AVR32] faster avr32 unaligned access
These functions depend on "result" being initalized to 0, but "result"
is not included as an input constraint to the inline assembly block
following its initialization, only as an output constraint. Thus gcc
thinks it doesn't need to initialize it, so result ends up undefined
if the "unless" condition is true.
This fixes an oops in sunrpc where the faulty atomics caused
rpciod_up() to not start the workqueue as it should.
Signed-off-by: Haavard Skinnemoen <hskinnemoen@atmel.com>
This patch adds register definitions, clocks and IRQs to the platform devices.
Signed-off-by: Hans-Christian Egtvedt <hcegtvedt@atmel.com>
Signed-off-by: Haavard Skinnemoen <hskinnemoen@atmel.com>
If we let unaligned word loads bypass the generic unaligned handling,
gcc may combine it with a swap.b instruction and turn it into a ldwsp
instruction, which does not work with unaligned addresses.
Revert the optimization to prevent the RNDIS driver from crashing.
Hopefully we'll figure something out later (it may be better to do the
optimization in gcc.)
Signed-off-by: Haavard Skinnemoen <hskinnemoen@atmel.com>
Split the SM platform device into separate platform devices for PM,
RTC, WDT and EIC. This is more correct according to the documentation
and allows us to simplify the code a little.
Also turn the EIC driver into a real platform driver.
Signed-off-by: Haavard Skinnemoen <hskinnemoen@atmel.com>
Acked-by: Hans-Christian Egtvedt <hcegtvedt@atmel.com>
Use a more conventional implementation for unaligned access, and include
an AT32AP-specific optimization: the CPU will handle unaligned words.
The result is always faster and smaller for 8, 16, and 32 bit values.
For 64 bit quantities, it's presumably larger.
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Haavard Skinnemoen <hskinnemoen@atmel.com>
* 'master' of ssh://master.kernel.org/pub/scm/linux/kernel/git/mchehab/v4l-dvb: (126 commits)
V4L/DVB (5847): Clean up schedule_timeout calls in cpia2 and ivtv code
V4L/DVB (5846): Clean up setting state and scheduling timeouts
V4L/DVB (5844): ivtv: add high volume debugging flag
V4L/DVB (5843): ivtv: fix missing signal_pending check.
V4L/DVB (5842): ivtv: Add locking to ensure stream setup is atomic.
V4L/DVB (5841): tveeprom: add support for Philips FQ1216LME MK3 tuner.
V4L/DVB (5840): fix dst and cx24123: tune() callback changed signess for delay
V4L/DVB (5838): dvb-core: Fix signedness warnings (gcc 4.1.1, kernel 2.6.22)
V4L/DVB (5837): stv0299: Fix signedness warning (gcc 4.1.1, kernel 2.6.22)
V4L/DVB (5836): dvb-ttpci: re-initialize aspect ratio and pan scan after arm crash
V4L/DVB (5835): saa7146/dvb-ttpci: Fix signedness warnings (gcc 4.1.1, kernel 2.6.22)
V4L/DVB (5834): dvb-core: fix signedness warnings and const stripping
V4L/DVB (5832): ir-common: optimize bit extract function
V4L/DVB (5831): stradis: use ARRAY_SIZE
V4L/DVB (5829): Firmware extract and loading for opera dvb-usb update
V4L/DVB (5828): Kconfig: Added GemTek USB radio and removed experimental dependency.
V4L/DVB (5826): Usbvision: video mux cleanup
V4L/DVB (5825): Alter the tuner type for the WinTV USB UK PAL model.
V4L/DVB (5824): Usbvision: Hauppauge WinTV USB SECAM_L fix
V4L/DVB (5821): Saa7134: add remote control support for LifeView FlyDVB-S LR300
...
* 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4:
ext4: extent macros cleanup
Fix compilation with EXT_DEBUG, also fix leXX_to_cpu conversions.
ext4: remove extra IS_RDONLY() check
ext4: Use is_power_of_2()
Use zero_user_page() in ext4 where possible
ext4: Remove 65000 subdirectory limit
ext4: Expand extra_inodes space per the s_{want,min}_extra_isize fields
ext4: Add nanosecond timestamps
jbd2: Move jbd2-debug file to debugfs
jbd2: Fix CONFIG_JBD_DEBUG ifdef to be CONFIG_JBD2_DEBUG
ext4: Set the journal JBD2_FEATURE_INCOMPAT_64BIT on large devices
ext4: Make extents code sanely handle on-disk corruption
ext4: copy i_flags to inode flags on write
ext4: Enable extents by default
Change on-disk format to support 2^15 uninitialized extents
write support for preallocated blocks
fallocate support in ext4
sys_fallocate() implementation on i386, x86_64 and powerpc
* 'master' of master.kernel.org:/pub/scm/linux/kernel/git/davem/net-2.6: (24 commits)
[NETFILTER]: xt_connlimit needs to depend on nf_conntrack
[NETFILTER]: ipt_iprange.h must #include <linux/types.h>
[IrDA]: Fix IrDA build failure
[ATM]: nicstar needs virt_to_bus
[NET]: move __dev_addr_discard adjacent to dev_addr_discard for readability
[NET]: merge dev_unicast_discard and dev_mc_discard into one
[NET]: move dev_mc_discard from dev_mcast.c to dev.c
[NETLINK]: negative groups in netlink_setsockopt
[PPPOL2TP]: Reset meta-data in xmit function
[PPPOL2TP]: Fix use-after-free
[PKT_SCHED]: Some typo fixes in net/sched/Kconfig
[XFRM]: Fix crash introduced by struct dst_entry reordering
[TCP]: remove unused argument to cong_avoid op
[ATM]: [idt77252] Rename CONFIG_ATM_IDT77252_SEND_IDLE to not resemble a Kconfig variable
[ATM]: [drivers] ioremap balanced with iounmap
[ATM]: [lanai] sram_test_word() must be __devinit
[ATM]: [nicstar] Replace C code with call to ARRAY_SIZE() macro.
[ATM]: Eliminate dead config variable CONFIG_BR2684_FAST_TRANS.
[ATM]: Replacing kmalloc/memset combination with kzalloc.
[NET]: gen_estimator deadlock fix
...
Move tuner callback function pointers out of struct tuner, into
struct tuner_operations.
Signed-off-by: Michael Krufky <mkrufky@linuxtv.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>
Individual tuner drivers are now allocating memory themselves for
their own private data structures. This changeset adds a release
callback to the tuner operations, so that newer drivers that may
require more complex data structures may release this private data
themselves.
Signed-off-by: Michael Krufky <mkrufky@linuxtv.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>
Create private data struct for device specific private data.
Signed-off-by: Michael Krufky <mkrufky@linuxtv.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>
* 'master' of master.kernel.org:/pub/scm/linux/kernel/git/davem/sparc-2.6:
[SPARC64]: Set vio->desc_buf to NULL after freeing.
[SPARC]: Mark sparc and sparc64 as not having virt_to_bus
[SPARC64]: Fix reset handling in VNET driver.
[SPARC64]: Handle reset events in vio_link_state_change().
[SPARC64]: Handle LDC resets properly in domain-services driver.
[SPARC64]: Massively simplify VIO device layer and support hot add/remove.
[SPARC64]: Simplify VNET probing.
[SPARC64]: Simplify VDC device probing.
[SPARC64]: Add basic infrastructure for MD add/remove notification.
This patch adds support for SAS Management Protocol (SMP) passthrough
support via bsg. aic94xx can use this.
Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>
The sas transport class attaches one bsg device to every SAS object
(host, device, expander, etc). LLDs can define a function to handle
SMP requests via sas_function_template::smp_handler.
Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>
Adds PCI_VENDOR_ID_BROCADE macro in include/linux/pci_ids.h file. This macro
is used in MPT Fusion FC drivers to support Brocade branded FC controllers
signed-off-by: Sathya Prakash <sathya.prakash@lsi.com>
Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>
This one was noticed by Gilbert Wu of Adaptec:
The libata core actually does the DMA mapping for you, so there has to
be an exception in the device drivers that *don't* do dma mapping for
ATA commands. However, since we've already done this, libsas must now
dma map any ATA commands that it wishes to issue ... and yes, this is a
horrible mess.
Additionally, the test in aic94xx for ATA protocols isn't quite right.
Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>
ATA devices need special handling for sas_task_abort. If the ATA command
came from SCSI, then we merely need to tell SCSI to abort the scsi_cmnd.
However, internal commands require a bit more work--we need to fill the qc
with the appropriate error status and complete the command, and eventually
post_internal will issue the actual ABORT TASK.
Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>
This patch adds a new field, lldd_task, to ata_queued_cmd so that libata
users such as libsas can associate some data with a qc. The particular
ambition with this patch is to associate a sas_task with a qc; that way,
if libata decides to timeout a command, we can come back (in
sas_ata_post_internal) and abort the sas task.
One question remains: Is it necessary to reset the phy on error, or will
the libata error handler take care of it? (Assuming that one is written,
of course.) This patch, as it is today, works well enough to clean
things up when an ATA device probe attempt fails halfway through the probe,
though I'm not sure this is always the right thing to do.
Signed-off-by: Darrick J. Wong <djwong@us.ibm.com>
Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>
This is a respin of my earlier patch that migrates the ATA support code
into a separate file. For now, the controversial linking bits have
been removed per James Bottomley's request for a patch that contains
only the migration diffs, which means that libsas continues to require
libata. I intend to address that problem in a separate patch.
This patch is against the aic94xx-sas-2.6 git tree, and it has been
sanity tested on my x206m with Seagate SATA and SAS disks without
uncovering any new problems.
Signed-off-by: Darrick J. Wong <djwong@us.ibm.com>
Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>
Hook the scsi_host_template functions in libsas to delegate
functionality to libata when appropriate.
Signed-off-by: Darrick J. Wong <djwong@us.ibm.com>
Misc code changes and merge fixes and update for libata->drivers/ata
move
Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>
An experimental patch for Xen allows guests to place their vcpu_info
structs anywhere. We try to use this to place the vcpu_info into the
PDA, which allows direct access.
If this works, then switch to using direct access operations for
irq_enable, disable, save_fl and restore_fl.
Signed-off-by: Jeremy Fitzhardinge <jeremy@xensource.com>
Cc: Chris Wright <chrisw@sous-sol.org>
Cc: Keir Fraser <keir@xensource.com>
The block device frontend driver allows the kernel to access block
devices exported exported by a virtual machine containing a physical
block device driver.
Signed-off-by: Ian Pratt <ian.pratt@xensource.com>
Signed-off-by: Christian Limpach <Christian.Limpach@cl.cam.ac.uk>
Signed-off-by: Chris Wright <chrisw@sous-sol.org>
Cc: Arjan van de Ven <arjan@infradead.org>
Cc: Greg KH <greg@kroah.com>
Cc: Jens Axboe <axboe@kernel.dk>
This communicates with the machine control software via a registry
residing in a controlling virtual machine. This allows dynamic
creation, destruction and modification of virtual device
configurations (network devices, block devices and CPUS, to name some
examples).
[ Greg, would you mind giving this a review? Thanks -J ]
Signed-off-by: Ian Pratt <ian.pratt@xensource.com>
Signed-off-by: Christian Limpach <Christian.Limpach@cl.cam.ac.uk>
Signed-off-by: Jeremy Fitzhardinge <jeremy@xensource.com>
Signed-off-by: Chris Wright <chrisw@sous-sol.org>
Cc: Greg KH <greg@kroah.com>
Add Xen 'grant table' driver which allows granting of access to
selected local memory pages by other virtual machines and,
symmetrically, the mapping of remote memory pages which other virtual
machines have granted access to.
This driver is a prerequisite for many of the Xen virtual device
drivers, which grant the 'device driver domain' restricted and
temporary access to only those memory pages that are currently
involved in I/O operations.
Signed-off-by: Jeremy Fitzhardinge <jeremy@xensource.com>
Signed-off-by: Ian Pratt <ian.pratt@xensource.com>
Signed-off-by: Christian Limpach <Christian.Limpach@cl.cam.ac.uk>
Signed-off-by: Chris Wright <chrisw@sous-sol.org>
Implement a Xen back-end for hvc console.
* * *
Add early printk support via hvc console, enable using
"earlyprintk=xen" on the kernel command line.
From: Gerd Hoffmann <kraxel@suse.de>
Signed-off-by: Jeremy Fitzhardinge <jeremy@xensource.com>
Signed-off-by: Chris Wright <chrisw@sous-sol.org>
Acked-by: Ingo Molnar <mingo@elte.hu>
Acked-by: Olof Johansson <olof@lixom.net>
