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Re: [Xen-users] system calls

>  I am pretty new to Xen and so any help would be appreciated.
>   Say a user level process make a "write" system call on a VM running on
> domain 1. Can anyone tell me the control flow (with the respect to the
> exact functions that will called in Xen) to make this sytem call work?

The guest is allowed to install its own trap handler, so the write() system 
call invokes the normal syscall handler as in normal Linux.

The difference is only at the block device layer: instead of talking directly 
to a disk, the domU will queue IO requests in shared memory, which are then 
handled by the backend driver (usually in dom0).

There are no calls within Xen required to make write() itself work.  The block 
device driver will use grant tables and event channel calls in order to 
transfer the data.


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