In the vCont packet, two of the command actions (C and S) take an
argument specifying the signal to be sent to the process/thread, which is
sent as an ASCII string of two hex digits which immediately follow the
'C' or 'S' character.
Our code for parsing this packet accidentally skipped the first of the
two bytes of the signal value, because it started parsing the hex string
at 'p + 1' when the preceding code had already moved past the 'C' or
'S' with "cur_action = *p++".
This meant that we would only do the right thing for signals below
10, and would misinterpret the rest. For instance, when the debugger
wants to send the process a SIGPROF (27 on x86-64) we mangle this into
a SIGSEGV (11).
Remove the accidental double increment.
Fixes: https://bugs.launchpad.net/qemu/+bug/1773743
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Message-id: 20201121210342.10089-1-peter.maydell@linaro.org
When record/replay does not uses overlays for storing the snapshots,
user is not capable of issuing reverse debugging commands.
This patch adds creation of the VM snapshot on the temporary
overlay image, when the debugger connects to QEMU.
Therefore the execution can be rewind to the moment
of the debugger connection while debugging the virtual machine.
Signed-off-by: Pavel Dovgalyuk <Pavel.Dovgalyuk@ispras.ru>
--
v6:
- dropped unused error processing (suggested by Philippe Mathieu-Daudé)
Message-Id: <160174524096.12451.11651270339216758643.stgit@pasha-ThinkPad-X280>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This patch adds support of the reverse continue operation for gdbstub.
Reverse continue finds the last breakpoint that would happen in normal
execution from the beginning to the current moment.
Implementation of the reverse continue replays the execution twice:
to find the breakpoints that were hit and to seek to the last breakpoint.
Reverse continue loads the previous snapshot and tries to find the breakpoint
since that moment. If there are no such breakpoints, it proceeds to
the earlier snapshot, and so on. When no breakpoints or watchpoints were
hit at all, execution stops at the beginning of the replay log.
Signed-off-by: Pavel Dovgalyuk <Pavel.Dovgalyuk@ispras.ru>
Message-Id: <160174522930.12451.6994758004725016836.stgit@pasha-ThinkPad-X280>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
GDB remote protocol supports two reverse debugging commands:
reverse step and reverse continue.
This patch adds support of the first one to the gdbstub.
Reverse step is intended to step one instruction in the backwards
direction. This is not possible in regular execution.
But replayed execution is deterministic, therefore we can load one of
the prior snapshots and proceed to the desired step. It is equivalent
to stepping one instruction back.
There should be at least one snapshot preceding the debugged part of
the replay log.
Signed-off-by: Pavel Dovgalyuk <Pavel.Dovgalyuk@ispras.ru>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
--
v4 changes:
- inverted condition in cpu_handle_guest_debug (suggested by Alex Bennée)
Message-Id: <160174522341.12451.1498758422543765253.stgit@pasha-ThinkPad-X280>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Meson doesn't enjoy the same flexibility we have with Make in choosing
the include path. In particular the tracing headers are using
$(build_root)/$(<D).
In order to keep the include directives unchanged,
the simplest solution is to generate headers with patterns like
"trace/trace-audio.h" and place forwarding headers in the source tree
such that for example "audio/trace.h" includes "trace/trace-audio.h".
This patch is too ugly to be applied to the Makefiles now. It's only
a way to separate the changes to the tracing header files from the
Meson rewrite of the tracing logic.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
object_get_canonical_path_component() returns a malloced copy of a
property name on success, null on failure.
19 of its 25 callers immediately free the returned copy.
Change object_get_canonical_path_component() to return the property
name directly. Since modifying the name would be wrong, adjust the
return type to const char *.
Drop the free from the 19 callers become simpler, add the g_strdup()
to the other six.
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Message-Id: <20200714160202.3121879-4-armbru@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Reviewed-by: Li Qiang <liq3ea@gmail.com>
While debugging over TCP is fairly straightforward now we have test
cases that want to orchestrate via make and currently a parallel build
fails as two processes can't use the same listening port. While system
emulation offers a wide cornucopia of connection methods thanks to the
chardev abstraction we are a little more limited for linux user.
Thankfully the programming API for a TCP socket and a local UNIX
socket is pretty much the same once it's set up.
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20200430190122.4592-7-alex.bennee@linaro.org>
We don't really need to track this fd beyond the initial creation of
the socket. We already know if the system has been initialised by
virtue of the gdbserver_state so lets remove it. This makes the later
re-factoring easier.
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20200430190122.4592-6-alex.bennee@linaro.org>
./gdbstub.c: In function ‘handle_query_thread_extra’:
/usr/include/glib-2.0/glib/glib-autocleanups.h:28:10:
error: ‘cpu_name’ may be used uninitialized in this function
[-Werror=maybe-uninitialized]
g_free (*pp);
^
./gdbstub.c:2063:26: note: ‘cpu_name’ was declared here
g_autofree char *cpu_name;
^
cc1: all warnings being treated as errors
Signed-off-by: Denis Plotnikov <dplotnikov@virtuozzo.com>
Message-Id: <20200326151407.25046-1-dplotnikov@virtuozzo.com>
Reported-by: Euler Robot <euler.robot@huawei.com>
Reported-by: Chen Qun <kuhn.chenqun@huawei.com>
Reviewed-by: Miroslav Rezanina <mrezanin@redhat.com>
Message-Id: <20200325092137.24020-1-kuhn.chenqun@huawei.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Message-Id: <20200403191150.863-7-alex.bennee@linaro.org>
Recently when debugging an arm32 system on qemu, I found sometimes the
single-step command (stepi) is not working. This can be reproduced by
below steps:
1) start qemu-system-arm -s -S .. and wait for gdb connection.
2) start gdb and connect to qemu. In my case, gdb gets a wrong value
(0x60) for PC, which is an another bug.
3) After connected, type 'stepi' and expect it will stop at next ins.
But, it has never stopped. This because:
1) We doesn't report ‘vContSupported’ feature to gdb explicitly and gdb
think we do not support it. In this case, gdb use a software breakpoint
to emulate single-step.
2) Since gdb gets a wrong initial value of PC, then gdb inserts a
breakpoint to wrong place (PC+4).
Not only for the arm target, Philippe has also encountered this on MIPS.
Probably gdb has different assumption for different architectures.
Since we do support ‘vContSupported’ query command, so let's tell gdb that
we support it.
Before this change, gdb send below 'Z0' packet to implement single-step:
gdb_handle_packet: Z0,4,4
After this change, gdb send "vCont;s.." which is expected:
gdb_handle_packet: vCont?
put_packet: vCont;c;C;s;S
gdb_handle_packet: vCont;s:p1.1;c:p1.-1
Signed-off-by: Changbin Du <changbin.du@gmail.com>
Tested-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Message-Id: <20200221002559.6768-1-changbin.du@gmail.com>
[AJB: fix for static gdbstub]
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Luc Michel <luc.michel@greensocs.com>
Message-Id: <20200316172155.971-29-alex.bennee@linaro.org>
Since we can now send packets of arbitrary length:
simplify gdb_monitor_write() and send the whole payload
in one packet.
Suggested-by: Luc Michel <luc.michel@greensocs.com>
Signed-off-by: Damien Hedde <damien.hedde@greensocs.com>
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20191211160514.58373-3-damien.hedde@greensocs.com>
Message-Id: <20200316172155.971-28-alex.bennee@linaro.org>
Remove the packet size upper limit by using a GByteArray
instead of a statically allocated array for last_packet.
Thus we can now send big packets.
Also remove the last_packet_len field and use last_packet->len
instead.
Signed-off-by: Damien Hedde <damien.hedde@greensocs.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Message-Id: <20191211160514.58373-2-damien.hedde@greensocs.com>
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20200316172155.971-27-alex.bennee@linaro.org>
Instead of passing a pointer to memory now just extend the GByteArray
to all the read register helpers. They can then safely append their
data through the normal way. We don't bother with this abstraction for
write registers as we have already ensured the buffer being copied
from is the correct size.
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Acked-by: David Gibson <david@gibson.dropbear.id.au>
Reviewed-by: Damien Hedde <damien.hedde@greensocs.com>
Message-Id: <20200316172155.971-15-alex.bennee@linaro.org>
This is in preparation for further re-factoring of the register API
with the rest of the code. Theoretically the read register function
could overwrite the MAX_PACKET_LENGTH buffer although currently all
registers are well within the size range.
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Damien Hedde <damien.hedde@greensocs.com>
Tested-by: Damien Hedde <damien.hedde@greensocs.com>
Message-Id: <20200316172155.971-10-alex.bennee@linaro.org>
Rather than having a static buffer replace str_buf with a GString
which we know can grow on demand. Convert the internal functions to
take a GString instead of a char * and length.
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Damien Hedde <damien.hedde@greensocs.com>
Tested-by: Damien Hedde <damien.hedde@greensocs.com>
Message-Id: <20200316172155.971-9-alex.bennee@linaro.org>
We only have one GDBState which should be allocated at the time we
process any commands. This will make further clean-up a bit easier.
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Damien Hedde <damien.hedde@greensocs.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Message-Id: <20200316172155.971-8-alex.bennee@linaro.org>
Instead of allocating make this entirely static. We shall reduce the
size of the structure in later commits and dynamically allocate parts
of it. We introduce an init and reset helper function to keep all the
manipulation in one place.
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Damien Hedde <damien.hedde@greensocs.com>
Message-Id: <20200316172155.971-7-alex.bennee@linaro.org>
Trying to attach a HMP monitor to a chardev that is already in use
results in a crash because monitor_init_hmp() passes &error_abort to
qemu_chr_fe_init():
$ ./x86_64-softmmu/qemu-system-x86_64 --chardev stdio,id=foo --mon foo --mon foo
QEMU 4.2.50 monitor - type 'help' for more information
(qemu) Unexpected error in qemu_chr_fe_init() at chardev/char-fe.c:220:
qemu-system-x86_64: --mon foo: Device 'foo' is in use
Abgebrochen (Speicherabzug geschrieben)
Fix this by allowing monitor_init_hmp() to return an error and passing
any error in qemu_chr_fe_init() to its caller instead of aborting.
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Message-Id: <20200224143008.13362-19-kwolf@redhat.com>
Acked-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
The Chardev events are listed in the QEMUChrEvent enum.
By using the enum in the IOEventHandler typedef we:
- make the IOEventHandler type more explicit (this handler
process out-of-band information, while the IOReadHandler
is in-band),
- help static code analyzers.
This patch was produced with the following spatch script:
@match@
expression backend, opaque, context, set_open;
identifier fd_can_read, fd_read, fd_event, be_change;
@@
qemu_chr_fe_set_handlers(backend, fd_can_read, fd_read, fd_event,
be_change, opaque, context, set_open);
@depends on match@
identifier opaque, event;
identifier match.fd_event;
@@
static
-void fd_event(void *opaque, int event)
+void fd_event(void *opaque, QEMUChrEvent event)
{
...
}
Then the typedef was modified manually in
include/chardev/char-fe.h.
Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Acked-by: Corey Minyard <cminyard@mvista.com>
Acked-by: Cornelia Huck <cohuck@redhat.com>
Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Message-Id: <20191218172009.8868-15-philmd@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Handling of the 'F' packet has been broken since commit
4b20fab101, which converted it to use
the new packet parsing infrastructure. Per the GDB RSP specification
https://sourceware.org/gdb/current/onlinedocs/gdb/The-F-Reply-Packet.html
the second parameter may be omitted, but the rewritten implementation
was failing to recognize this case. The result was that QEMU was
repeatedly resending the fileio request and ignoring GDB's replies of
successful completion. This patch restores the behavior of the
previous code in allowing the errno parameter to be omitted and
passing 0 to the callback in that case.
Signed-off-by: Sandra Loosemore <sandra@codesourcery.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20190827223317.8614-1-sandra@codesourcery.com>
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Since the '!' packet is not handled by the new infrastructure,
gdb_handle_packet() would call run_cmd_parser() with a NULL cmd_parser
value, which would lead to an unsupported packet ("$#00") being sent,
which could confuse the gdb client.
This also has a side-effect of speeding up the initial connection with
gdb.
Fixes: 3e2c12615b ("gdbstub: Implement deatch (D pkt) with new infra")
Signed-off-by: Ramiro Polla <ramiro.polla@gmail.com>
Message-Id: <20190805190901.14072-1-ramiro.polla@gmail.com>
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
sysemu/sysemu.h is a rather unfocused dumping ground for stuff related
to the system-emulator. Evidence:
* It's included widely: in my "build everything" tree, changing
sysemu/sysemu.h still triggers a recompile of some 1100 out of 6600
objects (not counting tests and objects that don't depend on
qemu/osdep.h, down from 5400 due to the previous two commits).
* It pulls in more than a dozen additional headers.
Split stuff related to run state management into its own header
sysemu/runstate.h.
Touching sysemu/sysemu.h now recompiles some 850 objects. qemu/uuid.h
also drops from 1100 to 850, and qapi/qapi-types-run-state.h from 4400
to 4200. Touching new sysemu/runstate.h recompiles some 500 objects.
Since I'm touching MAINTAINERS to add sysemu/runstate.h anyway, also
add qemu/main-loop.h.
Suggested-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Message-Id: <20190812052359.30071-30-armbru@redhat.com>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
[Unbreak OS-X build]
The refactoring of handle_set_reg missed the fact we previously had
responded with an empty packet when we were not using XML based
protocols. This broke the fallback behaviour for architectures that
don't have registers defined in QEMU's gdb-xml directory.
Revert to the previous behaviour and clean up the commentary for what
is going on.
Fixes: 62b3320bdd
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Tested-by: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Cc: Jon Doron <arilou@gmail.com>
Add a link to the remote protocol spec and an SPDX tag.
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Tested-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Basically, the context could get the MachineState reference via call
chains or unrecommended qdev_get_machine() in !CONFIG_USER_ONLY mode.
A local variable of the same name would be introduced in the declaration
phase out of less effort OR replace it on the spot if it's only used
once in the context. No semantic changes.
Signed-off-by: Like Xu <like.xu@linux.intel.com>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Message-Id: <20190518205428.90532-4-like.xu@linux.intel.com>
Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
Most callers know which monitor type they want to have. Instead of
calling monitor_init() with flags that can describe both types of
monitors, make monitor_init_{hmp,qmp}() public interfaces that take
specific bools instead of flags and call these functions directly.
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Message-Id: <20190613153405.24769-15-kwolf@redhat.com>
Reviewed-by: Markus Armbruster <armbru@redhat.com>
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Add a new query/set which changes the memory GDB sees to physical memory
only.
gdb> maint packet qqemu.PhyMemMode
will reply the current phy_mem_mode state (1 for enabled, 0 for disabled)
gdb> maint packet Qqemu.PhyMemMode:1
Will make GDB read/write only to physical memory, set to 0 to disable
Signed-off-by: Jon Doron <arilou@gmail.com>
Message-Id: <20190529064148.19856-21-arilou@gmail.com>
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Jon Doron <arilou@gmail.com>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Message-Id: <20190529064148.19856-20-arilou@gmail.com>
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Note: The user-mode thread-id has been correctly reported since bd88c780e6
Signed-off-by: Jon Doron <arilou@gmail.com>
Message-Id: <20190529064148.19856-19-arilou@gmail.com>
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
The generic set/query packets contains implementation for varioius
sub-commands which are required for GDB and also additional commands
which are QEMU specific.
To see which QEMU specific commands are available use the command
gdb> maintenance packet qqemu.Supported
Currently the only implemented QEMU specific command is the command
that sets the single step behavior.
gdb> maintenance packet qqemu.sstepbits
Will display the MASK bits used to control the single stepping.
gdb> maintenance packet qqemu.sstep
Will display the current value of the mask used when single stepping.
gdb> maintenance packet Qqemu.sstep:HEX_VALUE
Will change the single step mask.
Signed-off-by: Jon Doron <arilou@gmail.com>
Message-Id: <20190529064148.19856-18-arilou@gmail.com>
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Jon Doron <arilou@gmail.com>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Message-Id: <20190529064148.19856-16-arilou@gmail.com>
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Jon Doron <arilou@gmail.com>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Message-Id: <20190529064148.19856-14-arilou@gmail.com>
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Jon Doron <arilou@gmail.com>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Message-Id: <20190529064148.19856-13-arilou@gmail.com>
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Jon Doron <arilou@gmail.com>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Message-Id: <20190529064148.19856-12-arilou@gmail.com>
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Jon Doron <arilou@gmail.com>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Message-Id: <20190529064148.19856-11-arilou@gmail.com>
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Jon Doron <arilou@gmail.com>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Message-Id: <20190529064148.19856-7-arilou@gmail.com>
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Jon Doron <arilou@gmail.com>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Message-Id: <20190529064148.19856-6-arilou@gmail.com>
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Jon Doron <arilou@gmail.com>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Message-Id: <20190529064148.19856-5-arilou@gmail.com>
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Jon Doron <arilou@gmail.com>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Message-Id: <20190529064148.19856-4-arilou@gmail.com>
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Jon Doron <arilou@gmail.com>
Message-Id: <20190529064148.19856-3-arilou@gmail.com>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Jon Doron <arilou@gmail.com>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Message-Id: <20190529064148.19856-2-arilou@gmail.com>
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
No header includes qemu-common.h after this commit, as prescribed by
qemu-common.h's file comment.
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Message-Id: <20190523143508.25387-5-armbru@redhat.com>
[Rebased with conflicts resolved automatically, except for
include/hw/arm/xlnx-zynqmp.h hw/arm/nrf51_soc.c hw/arm/msf2-soc.c
block/qcow2-refcount.c block/qcow2-cluster.c block/qcow2-cache.c
target/arm/cpu.h target/lm32/cpu.h target/m68k/cpu.h target/mips/cpu.h
target/moxie/cpu.h target/nios2/cpu.h target/openrisc/cpu.h
target/riscv/cpu.h target/tilegx/cpu.h target/tricore/cpu.h
target/unicore32/cpu.h target/xtensa/cpu.h; bsd-user/main.c and
net/tap-bsd.c fixed up]
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Message-Id: <20190523143508.25387-3-armbru@redhat.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
In preparation for having some more common semihosting code let's
excise the current config magic from vl.c into its own file. We shall
later add more conditionals to the build configurations so we can
avoid building this if we don't need it.
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Tested-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
