Xen devel - Feb 2007 - [PATCH] [qemu] Modify mechanism by which serial console information is passed.

Modify the mechanism by which the serial console information is passed.

First, fix a potential memory leak in handling a realloc failure.

Next, the main point of this patch. qemu sets a store path of
<domain-path>/console/tty for every pty device that it creates.
This has the side effect of rewriting the entry if there is more than
one pty-based device.  The monitor, serial lines (can be several) and
parallel ports (can be several) may all use pty devices. In the face
of these multiple potential uses, the path may get overwritten and
contain incorrect information.  The routine writing the store entry
does not know which type of device (monitor, serial, parallel) that
it''s creating, and simply always writes the console/tty entry.

Resolve this issue by having the request to create the devices also
call a routine to create the store entries. The new code will create
entries specific to the device, and will also preserve the existing
console/tty entry (and prevent it from being overwritten). The entries
are:

<domain-path>/console/tty
<domain-path>/monitor/tty
<domain-path>/serial/<n>/tty
<domain-path>/parallel/<n>/tty

For instance, a selection from a xenstore-ls output:

    console = ""
     port = "3"
     limit = "1048576"
     tty = "/dev/pts/2"
    domid = "2"
    cpu = ""
     0 = ""
      availability = "online"
    serial = ""
     0 = ""
      tty = "/dev/pts/2"

The console/tty entry is preserved, and should match the serial/0/tty
entry for the case of a serial console mapped to a pty.

This patch makes each of the device entries unambiguous, provides
specific information for the additional devices, and maintains
compatibility with existing expectations about the console/tty
entry.

Signed-off-by: Ben Thomas (ben@virtualiron.com)

-- 
------------------------------------------------------------------------
Ben Thomas                                         Virtual Iron Software
bthomas@virtualiron.com                            Tower 1, Floor 2
978-849-1214                                       900 Chelmsford Street
                                                    Lowell, MA 01851


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