Hi,

On Tue Jul 24, 2012 at 19:15:17 +0800, ZhangEditing wrote:

I need to send megabytes of data from one virtual machine to another. I looked into source code of IPC streams for C++, but did not find any facility for sending the content of a large buffer (say, 512B).

Exchanging larger amounts of data between tasks (or VMs) is typically done using shared memory, i.e. a piece of memory shared between both (or more) parties and interrupts for notification.

I have also noticed the buffer registers in the UTCB, but I haven't figured out how to use it.

Buffer registers are used for mappings and not for data.

If there is a way to send the content of a large buffer, would you please reference me to the related documents? A simple example would be very helpful.

There a shared memory library, see l4/pkg/shmc and 4/pkg/examples/libs/shmc/. The lib just wraps around a dataspace that is shared between some tasks. There's also a more low-level example: l4/pkg/examples/libs/l4re/c++/shared_ds/. This example is a client and server one, where the client requests the dataspace from the server.

Adam