The windows socket functions look identical to the normal POSIX
sockets functions, but instead of setting errno, the caller needs
to call WSAGetLastError(). QEMU has tried to deal with this
incompatibility by defining a socket_error() method that callers
must use that abstracts the difference between WSAGetLastError()
and errno.
This approach is somewhat error prone though - many callers of
the sockets functions are just using errno directly because it
is easy to forget the need use a QEMU specific wrapper. It is
not always immediately obvious that a particular function will
in fact call into Windows sockets functions, so the dev may not
even realize they need to use socket_error().
This introduces an alternative approach to portability inspired
by the way GNULIB fixes portability problems. We use a macro to
redefine the original socket function names to refer to a QEMU
wrapper function. The wrapper function calls the original Win32
sockets method and then sets errno from the WSAGetLastError()
value.
Thus all code can simply call the normal POSIX sockets APIs are
have standard errno reporting on error, even on Windows. This
makes the socket_error() method obsolete.
We also bring closesocket & ioctlsocket into this approach. Even
though they are non-standard Win32 names, we can't wrap the normal
close/ioctl methods since there's no reliable way to distinguish
between a file descriptor and HANDLE in Win32.
Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
Historically QEMU has had a socket_error() macro that was
defined to map to WSASocketError(). The os-win32.h header
file would define errno constants that mapped to the
WSA error constants. This worked fine with Mingw32 since
its header files never defined any errno values, nor did
it even provide an errno.h. So callers of socket_error()
could match on traditional Exxxx constants and it would
all "just work".
With Mingw64 though, things work rather differently. First
there is an errno.h file which defines all the traditional
errno constants you'd expect from a UNIX platform. There
is then a winerror.h which defined the WSA error constants.
Crucially the WSAExxxx errno values in winerror.h do not
match the Exxxx errno values in error.h.
If QEMU had only imported winerror.h it would still work,
but the qemu/osdep.h file unconditionally imports errno.h.
So callers of socket_error() will get now WSAExxxx values
back and compare them to the Exxx constants. This will
always fail silently at runtime.
To solve this QEMU needs to stop assuming the WSAExxxx
constant values match the Exxx constant values. Thus the
socket_error() macro is turned into a small function that
re-maps WSAExxxx values into Exxx.
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
Clean up includes so that osdep.h is included first and headers
which it implies are not included manually.
This commit was created with scripts/clean-includes.
NB: If this commit breaks compilation for your out-of-tree
patchseries or fork, then you need to make sure you add
#include "qemu/osdep.h" to any new .c files that you have.
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Eric Blake <eblake@redhat.com>
Since gettimeofday() is used in this header file as a macro define,
include the function's define header file, to avoid compile warning
when other file include os-posix.h.
Signed-off-by: Wenchao Xia <wenchaoqemu@gmail.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com>
In certain scenario, latency induced by paging is significant and
memory locking is needed. Also, in the scenario with untrusted
guests, latency improvement due to mlock is desired.
This patch introduces a following new option to mlock guest and
qemu memory:
-realtime mlock=on|off
Signed-off-by: Satoru Moriya <satoru.moriya@hds.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Marcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-id: 1366382526-26146-1-git-send-email-pbonzini@redhat.com
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
Daniel P. Berrange
Peter Maydell
Wenchao Xia
Satoru Moriya
Paolo Bonzini