vichy wrote:
tr@fuckup:~/work$ ls -al /dev/ttyS*
crw-rw---- 1 root dialout 4, 64 2009-07-12 14:46 /dev/ttyS0
crw-rw---- 1 root dialout 4, 65 2009-07-12 14:46 /dev/ttyS1
crw-rw---- 1 root dialout 4, 66 2009-07-12 14:46 /dev/ttyS2
crw-rw---- 1 root dialout 4, 67 2009-07-12 14:46 /dev/ttyS3
as you can see the minor number of /dev/ttyS1 is 65.
if I remember correctly, each driver has to register its device node
with major, minor number.
In 8250.c, the 8250_init will assign each 8250 device with 8250
driver which minor number is 64.
if I have 2 8250 serial devices, it seems impossible I can driver my
second 8250 serial device through /dev/ttyS1, since driver is
registered for minor 64 but ttyS1 is minor 65.
It doesn't, I think you need to re-read the driver again. Each device, when registered via serial8250_register_port() will be attached to a different minor number. The minor number in serial8250_reg is the starting point for a block reservation of minor numbers to use for the 8250 serial devices and is reserved when the driver, not the individual ports, is registered. The number of minor numbers reserved is controlled by the ".nr" element, in this "UART_NR", which I believe defaults to 4.
Martyn
appreciate your help,
vichy
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