Re: event notification

[Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>]

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On Sat, Mar 06, 2010 at 07:12:02PM -0800, ravi kerur wrote:
> Hi,
> 
> Is there a mechanism available in Xen such that a kernel module in dom0 can
> register to it and when a VM(domU) is installed or deleted or suspend or
> resumed kernel module in domU can send notification to its counterpart in
> dom0. I have looked into xenbus mechanism used by PV drivers and it won't
> work for us. Inputs appreciated.

You can listen on udev events and see when a vif device has been added.
Also you can add pieces to the dom0 kernel to send uevents when a device
is suspended and do something.

Attached is a simple program to listen to all uevents..

> 
> Thanks
> -RK

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> Xen-devel mailing list
> Xen-devel@lists.xensource.com
> http://lists.xensource.com/xen-devel


[-- Attachment #2: listen.c --]
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#include <sys/socket.h>
#include <linux/netlink.h>
#include <stdio.h>
#include <string.h>
#define MAX_PAYLOAD 1024        /* maximum payload size */
struct sockaddr_nl src_addr;
int sock_fd;
static char buff[MAX_PAYLOAD];
ssize_t buflen;

int
main ()
{
  sock_fd = socket (PF_NETLINK, SOCK_DGRAM, NETLINK_KOBJECT_UEVENT);

  memset (&src_addr, 0, sizeof (src_addr));
  src_addr.nl_family = AF_NETLINK;
  src_addr.nl_pid = getpid ();  /* self pid */
  src_addr.nl_groups = 0xffffffff;

  printf ("Listen..\n");
  bind (sock_fd, (struct sockaddr *) &src_addr, sizeof (src_addr));
  printf ("Receiving..\n");
  while (1)
    {
      buflen = recv (sock_fd, &buff, sizeof (buff), 0);
      printf ("Got data: %d\n", buflen);
      int i, bufpos;
      char *key;
      for (i = 0, bufpos = 0; (bufpos < buflen) && i < MAX_PAYLOAD; i++)
        {
          key = &buff[bufpos];
          printf ("[%s]\n", key);
          bufpos += strlen (key) + 1;
        }
      memset (&buff, 0, MAX_PAYLOAD);
    }
  /* Close Netlink Socket */
  close (sock_fd);
  return 0;
}

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