docs/specs/ivshmem-spec.rst

5 The Inter-VM shared memory device (ivshmem) is designed to share a
8 shared memory area, it is modeled by QEMU as a PCI device exposing
46 Before QEMU 2.6.0, BAR2 can initially be invalid if the device is
53 Revision 0 of the device is not capable to tell guest software whether
54 it is configured for interrupts.
84 MSI-X capability: INTx is asserted when the bit-wise AND of Status and
85 Mask is non-zero and the device has no MSI-X capability.  Interrupt
87 is received.  Reading the register clears it.
89 IVPosition Register: if the device is not configured for interrupts,
90 this is zero.  Else, it is the device's ID (between 0 and 65535).
95 There is no good way for software to find out whether the device is
103 If the device is not configured for interrupts, the write is ignored.
105 If the interrupt hasn't completed setup, the write is ignored.  The
106 device is not capable to tell guest software whether setup is
110 interrupt vectors connected, the write is ignored.  The device is not
114 The peer's interrupt for this vector then becomes pending.  There is
116 operation is therefore impossible.
118 If the peer is a revision 0 device without MSI-X capability, its
119 Interrupt Status register is set to 1.  This asserts INTx unless
120 masked by the Interrupt Mask register.  The device is not capable to
162 notification on disconnect, and no new clients can connect.  There is
164 is not capable to tell guest software whether the server is still up.
166 Example server code is in contrib/ivshmem-server/.  Not to be used in
170 A standalone client is in contrib/ivshmem-client/.  It can be useful
179 The connection is one-way: the server sends messages to the client.
185 only when the character device is destroyed.
192 2. The client's ID.  This is unique among all clients of this server.
199 4. Connect notifications for existing other clients, if any.  This is
201    repeated N times.  Each repetition is accompanied by one file
203    vector 0,..,N-1, in order.  If the client is configured for fewer
204    vectors, it closes the extra file descriptors.  If it is configured
207 5. Interrupt setup.  This is the client's own ID, repeated N times.
208    Each repetition is accompanied by one file descriptor.  These are
210    order.  If the client is configured for fewer vectors, it closes
211    the extra file descriptors.  If it is configured for more, the
216 6. Connection / disconnection notification.  This is a peer ID.
228 * The protocol is poorly designed.