This patch allows more dynamic use of the qemu serial lines by allowing the Summagraphics port to float. I've discussed this with Don Dugger who did the Summagraphics work. This patch has no operational effect on existing configurations, but allows more serial lines to be used.

qemu will emulate up to 4 serial lines (COM1 - COM4). One of these lines supports a Summagraphics protocol. This has changed recently, and it's now always COM2. This patch allows the user to specify to qemu which lines should be serial lines, and the code will place the Summagraphics compatible line at just above the last specified serial line. qemu defaults serial line 0 (COM1) to be "vc", resulting in the Summagraphics support residing on COM2. This is in keeping with the current behavior.

The results, via qemu command line, are:

<none> COM2 -serial x COM2 -serial x -serial x COM3 -serial x -serial x -serial x COM4 -serial x -serial x -serial x -serial x <none>

The results are deterministic, and allow the use of up to 4 serial lines including none with Summagraphics support. There is no change from current behavior, unless requested.