Taimoor Mirza [Thu, 15 Aug 2013 18:13:28 +0000 (23:13 +0500)]
slirp: Port redirection option behave differently on Linux and Windows
port redirection code uses SO_REUSEADDR socket option before binding to
host port. Behavior of SO_REUSEADDR is different on Windows and Linux.
Relaunching QEMU with same host and guest port redirection values on Linux
throws error but on Windows it does not throw any error.
Problem is discussed in http://lists.gnu.org/archive/html/qemu-devel/2013-04/msg03089.html
Anthony Liguori [Fri, 30 Aug 2013 17:26:04 +0000 (12:26 -0500)]
Merge remote-tracking branch 'luiz/queue/qmp' into staging
# By Wenchao Xia (15) and Stefan Weil (1)
# Via Luiz Capitulino
* luiz/queue/qmp:
monitor: improve auto complete of "help" for single command in sub group
monitor: allow "help" show message for single command in sub group
monitor: support sub command in auto completion
monitor: refine monitor_find_completion()
monitor: support sub command in help
monitor: refine parse_cmdline()
monitor: code move for parse_cmdline()
monitor: avoid direct use of global variable *mon_cmds
monitor: split off monitor_data_init()
monitor: call sortcmdlist() only one time
monitor: avoid use of global *cur_mon in readline_completion()
monitor: avoid use of global *cur_mon in monitor_find_completion()
monitor: avoid use of global *cur_mon in block_completion_it()
monitor: avoid use of global *cur_mon in file_completion()
monitor: avoid use of global *cur_mon in cmd_completion()
monitor: Add missing attributes to local function
Anthony Liguori [Fri, 30 Aug 2013 17:25:56 +0000 (12:25 -0500)]
Merge remote-tracking branch 'borntraeger/tags/kdump' into staging
This is a set of patches dealing with kdump support for s390x/kvm.
kdump on s390x uses subcode 1 of diagnose 0x308 to put the hardware
in a defined state. This is different from a full reset, since it
does not touch all CPU registers.
These patches define the cpu resets, the subsystem reset a load
function and also wires up the "nmi" command to issue a RESTART
interrupt as defined in the z/Architecture principles of operation.
This allows recent guest kernels with properly setup userspace
to trigger kdump:
- via guest crash
- via nmi from the host
# gpg: Signature made Fri 30 Aug 2013 07:19:18 AM CDT using RSA key ID B5A61C7C
# gpg: Can't check signature: public key not found
# By Christian Borntraeger (5) and Eugene (jno) Dvurechenski (2)
# Via Christian Borntraeger
* borntraeger/tags/kdump:
s390: wire up nmi command to raise a RESTART interrupt on S390
s390: Implement load normal reset
s390/cpu: split CPU reset into architectured functions
s390: provide a cpu load normal function
s390: provide I/O subsystem reset
s390/kvm: basic implementation of diagnose 308 subcode 6
s390x/kvm: Fix switch/case indentation for handle_diag
s390: wire up nmi command to raise a RESTART interrupt on S390
There is the 'nmi' command that is used to trigger a guest dump via kdump feature on x86.
s390 uses RESTART interrupt to trigger kdump.
So, this patch provides a mean to use 'nmi' command on s390 to raise RESTART interrupt.
The CPU to receive the RESTART interrupt is the "default" one.
There is an infrastructure to select the "default" CPU using 'cpu' command.
The 'info cpus' command can be used to see which one is the "default".
In order to wire up the RESTART to 'nmi' command we had to:
1. implement the kvm_s390_cpu_restart function by exporting the existing code
2. implement s390_cpu_restart function as kvm-aware wrapper
3. modify the qmp_inject_nmi function to enable (for s390) the scan for
"default" CPU and call s390_cpu_restart for it;
3. fix some messages.
kdump on s390 uses a load normal reset to bring the system in a defined
state by doing a subsystem reset. The issuing CPUs will have an initial
CPU reset, all other CPUs will have a CPU reset as defined in POP (no
register content will change).
s390/cpu: split CPU reset into architectured functions
s390 provides several CPU resets:
- CPU reset, clears interrupts, stop processing, clears TLB, but does
not touch registers
- initial CPU reset, like CPU reset, but also clears PSW, prefix, FPC,
timer and control registers. It does not touch gprs, fprs and acrs (!)
- Power on reset: the full monty
wire up CPUClass reset to the full monty, but provide the lesser resets
as part of S390CPUClass.
Wenchao Xia [Tue, 27 Aug 2013 12:38:25 +0000 (20:38 +0800)]
monitor: support sub command in auto completion
This patch allows auto completion work normal for sub command case,
"info block [DEVICE]" can auto complete now, by re-enter the completion
function. In original code "info" is treated as a special case, now it
is treated as a sub command group, global variable info_cmds is not used
any more.
"help" command is still treated as a special case, since it is not a sub
command group but want to auto complete command in root command table.
Wenchao Xia [Tue, 27 Aug 2013 12:38:24 +0000 (20:38 +0800)]
monitor: refine monitor_find_completion()
In order to support sub command in auto completion, a reentrant function
is needed, so monitor_find_completion() is split into two parts. The
first part does parsing of user input which need to be done only once,
the second part does the auto completion job according to the parsing
result, which contains the necessary code to support sub command and
works as the reentrant function. The global "info_cmds" is still used
in second part, which will be replaced by sub command code later.
Wenchao Xia [Tue, 27 Aug 2013 12:38:23 +0000 (20:38 +0800)]
monitor: support sub command in help
The old code in help_cmd() uses global 'info_cmds' and treats it as a
special case. Actually 'info_cmds' is a sub command group of 'mon_cmds',
in order to avoid direct use of it, help_cmd() needs to change its work
mechanism to support sub command and not treat it as a special case
any more.
To support sub command, help_cmd() will first parse the input and then call
help_cmd_dump(), which works as a reentrant function. When it meets a sub
command, it simply enters the function again. Since help dumping needs to
know whole input to printf full help message include prefix, for example,
"help info block" need to printf prefix "info", so help_cmd_dump() takes all
args from input and extra parameter arg_index to identify the progress.
Another function help_cmd_dump_one() is introduced to printf the prefix
and command's help message.
Now help supports sub command, so later if another sub command group is
added in any depth, help will automatically work for it. Still "help info
block" will show error since command parser reject additional parameter,
which can be improved later. "log" is still treated as a special case.
Wenchao Xia [Tue, 27 Aug 2013 12:38:22 +0000 (20:38 +0800)]
monitor: refine parse_cmdline()
Since this function will be used by help_cmd() later, so improve
it to make it more generic and easier to use. free_cmdline_args()
is added too as paired function to free the result.
One change of this function is that, when the valid args in input
exceed the limit of MAX_ARGS, it fails now, instead of return with
MAX_ARGS of parsed args in old code. This should not impact much
since it is rare that user input many args in monitor's "help" and
auto complete scenario.
Wenchao Xia [Tue, 27 Aug 2013 12:38:21 +0000 (20:38 +0800)]
monitor: code move for parse_cmdline()
help_cmd() need this function later, so move it. get_str() is called by
parse_cmdline() so it is moved also. Some code style error reported by
check script, is also fixed.
Wenchao Xia [Tue, 27 Aug 2013 12:38:20 +0000 (20:38 +0800)]
monitor: avoid direct use of global variable *mon_cmds
New member *cmd_table is added in structure Monitor to avoid direct usage of
*mon_cmds. Now monitor have an associated command table, when global variable
*info_cmds is also discarded, structure Monitor would gain full control about
how to deal with user input.
Wenchao Xia [Tue, 27 Aug 2013 12:38:19 +0000 (20:38 +0800)]
monitor: split off monitor_data_init()
In qmp_human_monitor_command(), the monitor need to initialized for
basic functionalities, and later more init code will be added, so
split off this function. Note that it is different with QMP mode
monitor which accept json string from monitor's input,
qmp_human_monitor_command() retrieve the human style command from
QMP input, then send the command to a normal mode monitor.
Wenchao Xia [Tue, 27 Aug 2013 12:38:17 +0000 (20:38 +0800)]
monitor: avoid use of global *cur_mon in readline_completion()
Now all completion functions do not use *cur_mon any more, instead
they use rs->mon. In short, structure ReadLineState decide where
the complete action would be taken now.
Tested with the case that qemu have two telnet monitors, auto
completion function works normal.
Wenchao Xia [Tue, 27 Aug 2013 12:38:16 +0000 (20:38 +0800)]
monitor: avoid use of global *cur_mon in monitor_find_completion()
Parameter *mon is added, and local variable *mon added in previous patch
is removed. The caller readline_completion(), pass rs->mon as value, which
should be initialized in readline_init() called by monitor_init().
Wenchao Xia [Tue, 27 Aug 2013 12:38:13 +0000 (20:38 +0800)]
monitor: avoid use of global *cur_mon in cmd_completion()
A new local variable *mon is added in monitor_find_completion()
to make compile pass, which will be removed later in
conversion patch for monitor_find_completion().
Anthony Liguori [Thu, 29 Aug 2013 22:20:17 +0000 (17:20 -0500)]
Merge remote-tracking branch 'sweil/mingw' into stable-1.5
# By Stefan Weil
# Via Stefan Weil
* sweil/mingw:
gtk: Remove unused include statements which are not portable
w32: Add an icon resource
w32: Fix broken out-of-tree builds (missing version.o)
Anthony Liguori [Thu, 29 Aug 2013 22:19:19 +0000 (17:19 -0500)]
Merge remote-tracking branch 'mst/tags/for_anthony' into stable-1.5
pc,pci,virtio fixes and cleanups
This includes pc and pci cleanups, future-proofing of ROM files,
and a virtio bugfix correcting splice on virtio console.
Signed-off-by: Michael S. Tsirkin <[email protected]>
# gpg: Signature made Mon 26 Aug 2013 01:34:20 AM CDT using RSA key ID D28D5469
# gpg: Can't check signature: public key not found
# By Markus Armbruster (5) and others
# Via Michael S. Tsirkin
* mst/tags/for_anthony:
virtio: virtqueue_get_avail_bytes: fix desc_pa when loop over the indirect descriptor table
pc_piix: Kill pc_init1() memory region args
pc: pc_compat_1_4() now can call pc_compat_1_5()
pc: Create pc_compat_*() functions
pc: Kill pc_init_pci_1_0()
pc: Don't explode QEMUMachineInitArgs into local variables needlessly
pc: Don't prematurely explode QEMUMachineInitArgs
ppc: Don't duplicate QEMUMachineInitArgs in PPCE500Params
ppc: Don't explode QEMUMachineInitArgs into local variables needlessly
sun4: Don't prematurely explode QEMUMachineInitArgs
q35: Add PCIe switch to example q35 configuration
loader: store FW CFG ROM files in RAM
arch_init: align MR size to target page size
pc: cleanup 1.4 compat support
Indeed, remove it entirely and remove the is_tcg_gen_code check
from GETPC_EXT.
Fixes https://bugs.launchpad.net/qemu/+bug/1218098 wherein a call
to a "normal" helper function performed a sequence of tail calls
all the way into the memory helper functions, leading to a stack
frame in which the memory helper function appeared to be called
directly from tcg.
In get_physical_address() is a qemu_log() call inside an #if 0 block.
When enabled the following build error is hit:
target-mips/helper.c In function ‘get_physical_address’:
target-mips/helper.c:220:13: error: format ‘%x’ expects argument of type ‘unsigned int’, but argument 5 has type ‘hwaddr’ [-Werror=format]
Fix the *physical (hwaddr) formatting by using "%"HWADDR_PRIx instead of
TARGET_FMT_lx.
Commit 0b516ef0dfad9a7b34c675c98e8ec92ab4d38466 added version.o to all
executables, but broke out-of-tree builds: for those builds the pattern
rule %.o: %.rc from rules.mak does not match, so version.o was no longer
built.
Discontinue the jump-around-jump-to-jump scheme, trading it for a single
immediate move instruction. The two extra jumps always consume 7 bytes,
whereas the immediate move is either 5 or 7 bytes depending on where the
code_gen_buffer gets located.
Avoid a loop in the tlb_fill path; the fill will either succeed or
generate an exception.
Inline the slow_ld/st function; it was a complete copy of the main
helper except for the actual cross-page unaligned code, and the
compiler was inlining it anyway.
Add unlikely markers optimizing for the most common case of simple
tlb miss.
Make sure the compiler can optimize away the unaligned paths for a
1 byte access.
Anthony Liguori [Mon, 26 Aug 2013 14:19:50 +0000 (09:19 -0500)]
Merge remote-tracking branch 'stefanha/block' into staging
# By Alex Bligh (32) and others
# Via Stefan Hajnoczi
* stefanha/block: (42 commits)
win32-aio: drop win32_aio_flush_cb()
aio-win32: replace incorrect AioHandler->opaque usage with ->e
aio / timers: remove dummy_io_handler_flush from tests/test-aio.c
aio / timers: Remove legacy interface
aio / timers: Switch entire codebase to the new timer API
aio / timers: Add scripts/switch-timer-api
aio / timers: Add test harness for AioContext timers
aio / timers: convert block_job_sleep_ns and co_sleep_ns to new API
aio / timers: Convert rtc_clock to be a QEMUClockType
aio / timers: Remove main_loop_timerlist
aio / timers: Rearrange timer.h & make legacy functions call non-legacy
aio / timers: Add qemu_clock_get_ms and qemu_clock_get_ms
aio / timers: Remove legacy qemu_clock_deadline & qemu_timerlist_deadline
aio / timers: Remove alarm timers
aio / timers: Add documentation and new format calls
aio / timers: Use all timerlists in icount warp calculations
aio / timers: Introduce new API timer_new and friends
aio / timers: On timer modification, qemu_notify or aio_notify
aio / timers: Convert mainloop to use timeout
aio / timers: Convert aio_poll to use AioContext timers' deadline
...
yinyin [Thu, 22 Aug 2013 06:47:16 +0000 (14:47 +0800)]
virtio: virtqueue_get_avail_bytes: fix desc_pa when loop over the indirect descriptor table
virtqueue_get_avail_bytes: when found a indirect desc, we need loop over it.
/* loop over the indirect descriptor table */
indirect = 1;
max = vring_desc_len(desc_pa, i) / sizeof(VRingDesc);
num_bufs = i = 0;
desc_pa = vring_desc_addr(desc_pa, i);
But, It init i to 0, then use i to update desc_pa. so we will always get:
desc_pa = vring_desc_addr(desc_pa, 0);
the last two line should swap.
The script massages the output produced for architectures that are
not supported internally by qemu though an external objdump program
for disassembly.
Stefan Hajnoczi [Thu, 22 Aug 2013 13:28:36 +0000 (15:28 +0200)]
win32-aio: drop win32_aio_flush_cb()
The io_flush argument to qemu_aio_set_event_notifier() has been removed
since the block layer learnt to drain requests by itself. Fix the
Windows build for win32-aio.o by updating the
qemu_aio_set_event_notifier() call and dropping win32_aio_flush_cb().
Stefan Hajnoczi [Thu, 22 Aug 2013 13:28:35 +0000 (15:28 +0200)]
aio-win32: replace incorrect AioHandler->opaque usage with ->e
The AioHandler->opaque field does not exist in aio-win32.c. The code
that uses it was incorrectly copied from aio-posix.c. For Windows we
can use AioHandler->e to match against AioContext->notifier.
This patch fixes the Windows build for aio-win32.o.
Alex Bligh [Wed, 21 Aug 2013 15:03:03 +0000 (16:03 +0100)]
aio / timers: Remove main_loop_timerlist
Now we have timerlistgroups implemented and main_loop_tlg, we
no longer need the concept of a default timer list associated
with each clock. Remove it and simplify initialisation of
clocks and timer lists.
Alex Bligh [Wed, 21 Aug 2013 15:02:57 +0000 (16:02 +0100)]
aio / timers: Use all timerlists in icount warp calculations
Notify all timerlists derived from vm_clock in icount warp
calculations.
When calculating timer delay based on vm_clock deadline, use
all timerlists.
For compatibility, maintain an apparent bug where when using
icount, if no vm_clock timer was set, qemu_clock_deadline
would return INT32_MAX and always set an icount clock expiry
about 2 seconds ahead.
NB: thread safety - when different timerlists sit on different
threads, this will need some locking.
Alex Bligh [Wed, 21 Aug 2013 15:02:54 +0000 (16:02 +0100)]
aio / timers: Convert mainloop to use timeout
Convert mainloop to use timeout from default timerlist group
(i.e. the current 3 static timers)
main-loop.c produces a (possibly spurious) warning about
multiple iterations. Adapt the way this works for a signed
timeout and make the warning a bit safer.
Alex Bligh [Wed, 21 Aug 2013 15:02:53 +0000 (16:02 +0100)]
aio / timers: Convert aio_poll to use AioContext timers' deadline
Convert aio_poll to use deadline based on AioContext's timers.
aio_poll has been changed to return accurately whether progress
has occurred. Prior to this commit, aio_poll always returned
true if g_poll was entered, whether or not any progress was
made. This required a change to tests/test-aio.c where an
assert was backwards.
Alex Bligh [Wed, 21 Aug 2013 15:02:48 +0000 (16:02 +0100)]
aio / timers: Add QEMUTimerListGroup and helper functions
Add QEMUTimerListGroup and helper functions, to represent
a QEMUTimerList associated with each clock. Add a default
QEMUTimerListGroup representing the default timer lists
which are not associated with any other object (e.g.
an AioContext as added by future patches).
Alex Bligh [Wed, 21 Aug 2013 15:02:47 +0000 (16:02 +0100)]
aio / timers: Untangle include files
include/qemu/timer.h has no need to include main-loop.h and
doing so causes an issue for the next patch. Unfortunately
various files assume including timers.h will pull in main-loop.h.
Untangle this mess.
Alex Bligh [Wed, 21 Aug 2013 15:02:46 +0000 (16:02 +0100)]
aio / timers: Split QEMUClock into QEMUClock and QEMUTimerList
Split QEMUClock into QEMUClock and QEMUTimerList so that we can
have more than one QEMUTimerList associated with the same clock.
Introduce a main_loop_timerlist concept and make existing
qemu_clock_* calls that actually should operate on a QEMUTimerList
call the relevant QEMUTimerList implementations, using the clock's
default timerlist. This vastly reduces the invasiveness of this
change and means the API stays constant for existing users.
Introduce a list of QEMUTimerLists associated with each clock
so that reenabling the clock can cause all the notifiers
to be called. Note the code to do the notifications is added
in a later patch.
Switch QEMUClockType to an enum. Remove global variables vm_clock,
host_clock and rt_clock and add compatibility defines. Do not
fix qemu_next_alarm_deadline as it's going to be deleted.
Add qemu_clock_use_for_deadline to indicate whether a particular
clock should be used for deadline calculations. When use_icount
is true, vm_clock should not be used for deadline calculations
as it does not contain a nanosecond count. Instead, icount
timeouts come from the execution thread doing aio_notify or
qemu_notify as appropriate. This function is used in the next
patch.
Anthony Liguori [Thu, 22 Aug 2013 14:29:25 +0000 (09:29 -0500)]
Merge remote-tracking branch 'luiz/queue/qmp' into staging
# By Laszlo Ersek (8) and others
# Via Luiz Capitulino
* luiz/queue/qmp:
scripts/qapi.py: Avoid syntax not supported by Python 2.4
monitor: print the invalid char in error message
OptsVisitor: introduce unit tests, with test cases for range flattening
add "test-int128" and "test-bitops" to .gitignore
OptsVisitor: don't try to flatten overlong integer ranges
OptsVisitor: opts_type_uint64(): recognize intervals when LM_IN_PROGRESS
OptsVisitor: rebase opts_type_uint64() to parse_uint_full()
OptsVisitor: opts_type_int(): recognize intervals when LM_IN_PROGRESS
OptsVisitor: introduce list modes for interval flattening
OptsVisitor: introduce basic list modes
Convert stderr message calling error_get_pretty() to error_report()
Anthony Liguori [Thu, 22 Aug 2013 14:29:13 +0000 (09:29 -0500)]
Merge remote-tracking branch 'jliu/or32' into staging
# By Jia Liu
# Via Jia Liu
* jliu/or32:
hw/openrisc: Avoid undefined shift in openrisc_pic_cpu_handler()
hw/openrisc: Fix masking in openrisc_pic_cpu_handler()
hw/openrisc: Avoid using uninitialised variable 'entry'
Alex Bligh [Wed, 21 Aug 2013 15:02:39 +0000 (16:02 +0100)]
aio / timers: Rename qemu_timer_* functions
Rename four functions in preparation for new API.
Rename qemu_timer_expired to timer_expired
Rename qemu_timer_expire_time_ns to timer_expire_time_ns
Rename qemu_timer_pending to timer_pending
Rename qemu_timer_expired_ns to timer_expired_ns
Paolo Bonzini [Mon, 19 Aug 2013 10:54:28 +0000 (18:54 +0800)]
vmdk: support vmfs files
VMware ESX hosts also use different create and extent types for flat
files, respectively "vmfs" and "VMFS". This is not documented, but it
can be found at http://kb.vmware.com/kb/10002511 (Recreating a missing
virtual machine disk (VMDK) descriptor file).
Fam Zheng [Mon, 19 Aug 2013 10:54:27 +0000 (18:54 +0800)]
vmdk: support vmfsSparse files
VMware ESX hosts use a variant of the VMDK3 format, identified by the
vmfsSparse create type ad the VMFSSPARSE extent type.
It has 16 KB grain tables (L2) and a variable-size grain directory (L1).
In addition, the grain size is always 512, but that is not a problem
because it is included in the header.
The format of the extents is documented in the VMDK spec. The format
of the descriptor file is not documented precisely, but it can be
found at http://kb.vmware.com/kb/10026353 (Recreating a missing virtual
machine disk (VMDK) descriptor file for delta disks).
With these patches, vmfsSparse files only work if opened through the
descriptor file. Data files without descriptor files, as far as I
could understand, are not supported by ESX.
Signed-off-by: Paolo Bonzini <[email protected]> Signed-off-by: Fam Zheng <[email protected]>
--
v2: Rebase to patch 01.
Change le64_to_cpu to le32_to_cpu.
Rename vmdk_open_vmdk3 to vmdk_open_vmfs_sparse, which represents the
current usage of this format.
Fam Zheng [Thu, 22 Aug 2013 07:36:59 +0000 (15:36 +0800)]
block: better error message for read only format name
When user tries to use read-only whitelist format in the command line
option, failure message was "'foo' invalid format". It might be invalid
only for writable, but valid for read-only, so it is confusing. Give the
user easier to understand information.
Notice the open -g option to set bs->growable. This means you can
read/write beyond end of file. Reading beyond end of file is supposed
to produce zeroes.
We rely on this behavior in qcow2_create2() during qcow2 image
creation. We create a new file and then write the qcow2 header
structure using bdrv_pwrite(). Since QCowHeader is not a multiple of
sector size, block.c first uses bdrv_read() on the empty file to fetch
the first sector (should be all zeroes).
Here is the output from the qemu-io NBD example above:
$ qemu-io -c 'open -g nbd+unix:///?socket=/tmp/nbd.sock' -c 'read -v 0 512' 00000000: ab ab ab ab ab ab ab ab ab ab ab ab ab ab ab ab ................ 00000010: ab ab ab ab ab ab ab ab ab ab ab ab ab ab ab ab ................ 00000020: ab ab ab ab ab ab ab ab ab ab ab ab ab ab ab ab ................
...
We are not zeroing the buffer! As a result qcow2 image creation on top
of protocols is not guaranteed to work even when file creation is
supported by the protocol.
[Adapted this patch to use bs->zero_beyond_eof.
-- Stefan]
Asias He [Thu, 22 Aug 2013 07:24:14 +0000 (15:24 +0800)]
block: Introduce bs->zero_beyond_eof
In 4146b46c42e0989cb5842e04d88ab6ccb1713a48 (block: Produce zeros when
protocols reading beyond end of file), we break qemu-iotests ./check
-qcow2 022. This happens because qcow2 temporarily sets ->growable = 1
for vmstate accesses (which are stored beyond the end of regular image
data).
We introduce the bs->zero_beyond_eof to allow qcow2_load_vmstate() to
disable ->zero_beyond_eof temporarily in addition to enable ->growable.
[Since the broken patch "block: Produce zeros when protocols reading
beyond end of file" has not been merged yet, I have applied this fix
*first* and will then apply the next patch to keep the tree bisectable.
-- Stefan]
Eduardo Habkost [Wed, 21 Aug 2013 18:14:45 +0000 (15:14 -0300)]
pc_piix: Kill pc_init1() memory region args
All callers always use the same values (get_system_memory(),
get_system_io()), so the parameters are pointless.
If one day we decide to eliminate get_system_memory() and
get_system_io(), we will be able to do that more easily by adding the
values to struct QEMUMachineInitArgs.
Eduardo Habkost [Wed, 21 Aug 2013 18:14:43 +0000 (15:14 -0300)]
pc: Create pc_compat_*() functions
Making the older compat functions call the newer compat functions at the
beginning allows the older functions undo what's done by newer compat
functions. e.g.: pc_compat_1_4() will be able to call pc_compat_1_5()
and then set has_pvpanic=false.