Re: [Qemu-devel] [RFC 2/5] block: add new command line parameter that and protocol description
On Tue, May 01, 2012 at 04:31:44PM +0100, Stefan Hajnoczi wrote:
From: Anthony Liguori aligu...@us.ibm.com
Signed-off-by: Anthony Liguori aligu...@us.ibm.com
Signed-off-by: Stefan Hajnoczi stefa...@linux.vnet.ibm.com
---
qemu-options.hx | 42 ++
1 file changed, 42 insertions(+)
diff --git a/qemu-options.hx b/qemu-options.hx
index a169792..ccf4d1d 100644
--- a/qemu-options.hx
+++ b/qemu-options.hx
@@ -2724,6 +2724,48 @@ DEF(qtest-log, HAS_ARG, QEMU_OPTION_qtest_log,
-qtest-log LOG specify tracing options\n,
QEMU_ARCH_ALL)
+DEF(open-hook-fd, HAS_ARG, QEMU_OPTION_open_hook_fd,
+-open-hook-fd fd\n
+delegate opens to external process using fd\n,
QEMU_ARCH_ALL)
+STEXI
+@item -open-hook-fd @var{fd}
+@findex -open-hook-fd
+Delegates open()s to an external process using @varfd to communicate
commands.
+@varfd should be an open Unix Domain socket pipe that file descriptors can
be
+received from. The protocol the socket uses is a simple request/response
initiated
+by the client. All integers are in host byte order. It is assumed that
this protocol
+is only ever used on the same physical machine. It is currently defined as:
+
+u32 message_size
+u32 command
+u8 payload[message_size - 8]
+
+The contents of payload depend on command. Currently the following commands
are
+defined:
+
+1. QEMU_OPEN (1)
+
+The full message will be:
+
+u32 message_size
+u32 command = 1
+u32 flags (O_ flags defined by libc)
+u32 mode (mode_t flags as defined by libc)
+u16 filename_len;
+u8 filename[filename_len]
I think this should include the ID of the backend of the drive wanting
this file opened, so you can reliably match up to the -drive that mgmt
configured at startup. ie not have to search through every single
device in the guest all their backing files to find if there is a
match.
Regards,
Daniel
--
|: http://berrange.com -o-http://www.flickr.com/photos/dberrange/ :|
|: http://libvirt.org -o- http://virt-manager.org :|
|: http://autobuild.org -o- http://search.cpan.org/~danberr/ :|
|: http://entangle-photo.org -o- http://live.gnome.org/gtk-vnc :|
Re: [Qemu-devel] [RFC 2/5] block: add new command line parameter that and protocol description
On Tue, May 01, 2012 at 04:31:44PM +0100, Stefan Hajnoczi wrote:
From: Anthony Liguori aligu...@us.ibm.com
Signed-off-by: Anthony Liguori aligu...@us.ibm.com
Signed-off-by: Stefan Hajnoczi stefa...@linux.vnet.ibm.com
---
qemu-options.hx | 42 ++
1 file changed, 42 insertions(+)
diff --git a/qemu-options.hx b/qemu-options.hx
index a169792..ccf4d1d 100644
--- a/qemu-options.hx
+++ b/qemu-options.hx
@@ -2724,6 +2724,48 @@ DEF(qtest-log, HAS_ARG, QEMU_OPTION_qtest_log,
-qtest-log LOG specify tracing options\n,
QEMU_ARCH_ALL)
+DEF(open-hook-fd, HAS_ARG, QEMU_OPTION_open_hook_fd,
+-open-hook-fd fd\n
+delegate opens to external process using fd\n,
QEMU_ARCH_ALL)
+STEXI
+@item -open-hook-fd @var{fd}
+@findex -open-hook-fd
+Delegates open()s to an external process using @varfd to communicate
commands.
+@varfd should be an open Unix Domain socket pipe that file descriptors can
be
+received from. The protocol the socket uses is a simple request/response
initiated
+by the client. All integers are in host byte order. It is assumed that
this protocol
+is only ever used on the same physical machine. It is currently defined as:
+
+u32 message_size
+u32 command
+u8 payload[message_size - 8]
+
+The contents of payload depend on command. Currently the following commands
are
+defined:
+
+1. QEMU_OPEN (1)
+
+The full message will be:
+
+u32 message_size
+u32 command = 1
+u32 flags (O_ flags defined by libc)
+u32 mode (mode_t flags as defined by libc)
+u16 filename_len;
+u8 filename[filename_len]
+
+The server will then respond with:
+
+u32 message_size
+u32 command = 1
+s32 result
If we're going for a binary protocol, then I'd like to see it defined
based on the XDR specification, so we can auto-generate our data
marshallers/demarshallers using existing tools / libraries and not
have to write something custom by hand. Your spec here is close enough
that it would not be significant work. The changes would be
- Everything is always big-endian
- Each field has 4-byte alignment
- Strings would have a u32 length, and the payload padded with NUL
to the 4 byte boundary
Daniel.
--
|: http://berrange.com -o-http://www.flickr.com/photos/dberrange/ :|
|: http://libvirt.org -o- http://virt-manager.org :|
|: http://autobuild.org -o- http://search.cpan.org/~danberr/ :|
|: http://entangle-photo.org -o- http://live.gnome.org/gtk-vnc :|
[Qemu-devel] [RFC 2/5] block: add new command line parameter that and protocol description
From: Anthony Liguori aligu...@us.ibm.com
Signed-off-by: Anthony Liguori aligu...@us.ibm.com
Signed-off-by: Stefan Hajnoczi stefa...@linux.vnet.ibm.com
---
qemu-options.hx | 42 ++
1 file changed, 42 insertions(+)
diff --git a/qemu-options.hx b/qemu-options.hx
index a169792..ccf4d1d 100644
--- a/qemu-options.hx
+++ b/qemu-options.hx
@@ -2724,6 +2724,48 @@ DEF(qtest-log, HAS_ARG, QEMU_OPTION_qtest_log,
-qtest-log LOG specify tracing options\n,
QEMU_ARCH_ALL)
+DEF(open-hook-fd, HAS_ARG, QEMU_OPTION_open_hook_fd,
+-open-hook-fd fd\n
+delegate opens to external process using fd\n,
QEMU_ARCH_ALL)
+STEXI
+@item -open-hook-fd @var{fd}
+@findex -open-hook-fd
+Delegates open()s to an external process using @varfd to communicate
commands.
+@varfd should be an open Unix Domain socket pipe that file descriptors can be
+received from. The protocol the socket uses is a simple request/response
initiated
+by the client. All integers are in host byte order. It is assumed that this
protocol
+is only ever used on the same physical machine. It is currently defined as:
+
+u32 message_size
+u32 command
+u8 payload[message_size - 8]
+
+The contents of payload depend on command. Currently the following commands
are
+defined:
+
+1. QEMU_OPEN (1)
+
+The full message will be:
+
+u32 message_size
+u32 command = 1
+u32 flags (O_ flags defined by libc)
+u32 mode (mode_t flags as defined by libc)
+u16 filename_len;
+u8 filename[filename_len]
+
+The server will then respond with:
+
+u32 message_size
+u32 command = 1
+s32 result
+
+If result is 0, the value will be negated errno value as defined in errno.h.
If
+result is equal to 0, then there will also be a file descriptor available via
SCM_RIGHTS
+in the extended sendmsg data.
+
+ETEXI
+
HXCOMM This is the last statement. Insert new options before this line!
STEXI
@end table
--
1.7.10
