[Xen-devel] [PATCH] Enable PCI serial devices for console messages

["Dugger, Donald D" <donald.d.dugger@xxxxxxxxx>]

The basic issue is that some PCI serial devices use a non-standard crystal to 
control the baud rate divisor.  This patch enhances the `com' parameter to 
enable you to specify the crystal frequency used by the serial device.  Since 
this parameter already allows you to specify I/O address and IRQ this is all 
that is needed to get a PCI serial device to work.  With this patch the `com' 
parameter is now defined as:

        comN=BBB,NPS,III/CCC,IRQ

Where `N' is the com port number (1 or 2), `BBB' is the baud rate, `NPS' is the 
number of bits per character, parity and number of stop bits (defaults to 8n1), 
III is the I/O port address (defaults to 0x3f8 for `com1' and 0x2f8 for 
`com2'), `CCC' is the crystal frequency (typically the highest baud rate 
supported by the UART, defaults to 115200) and `IRQ' is the interrupt number 
(defaults to 4 for `com1' and 3 for `com2').  Note that if you specify 0 for 
`IRQ' Xen will run the serial device in polled mode, obviating the need for 
interrupts (an advantage since this is the only way I was able to get my PCI 
serial device to work).

As an example, I am using the xen boot command:

        kernel /xen.gz com1=115200,8n1,0xe880/921600,0 console=com1

Signed-off-by: Don Dugger <donald.d.dugger@xxxxxxxxx>

--
Don Dugger
"Censeo Toto nos in Kansa esse decisse." - D. Gale
Donald.D.Dugger@xxxxxxxxx`
Ph: (303)443-3786

Attachment: pci_serial-xen-1016.patch
Description: pci_serial-xen-1016.patch

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