vichy wrote:
2009/7/14, Martyn Welch <martyn.welch@xxxxxxxxxxx>:
vichy wrote:
Dear all:
while tracing 8250.c, serial8250_init, I find all the ports are
assigned with the same uart_driver 8250 as below:
static struct uart_driver serial8250_reg = {
.owner = THIS_MODULE,
.driver_name = "serial",
.dev_name = "ttyS",
.major = TTY_MAJOR,
.minor = 64,
.nr = UART_NR,
.cons = SERIAL8250_CONSOLE,
};
what make me curious is the minor# above is 64, but the minor number
of /dev/ttyS1 is 65.
Numbering starts at 0, the first serial port (/dev/ttyS0) is assigned minor
64.
hi:
Thanks for your reminding.
What makes me curious is how kernel connect /dev/ttyS1 with serial driver?
By port number or minor number?
I can see the minor of /dev/ttyS0 is 64, and serial driver is also
register as minor 64.
But what about /dev/ttyS1?
Ah, I think I understand. The above structure is related to the 8250 driver, which is shared by all of the serial ports conforming to the "8250 type" of serial port.
Looking at serial8250_register_port() (http://lxr.linux.no/linux+v2.6.30/drivers/serial/8250.c#L3075), which seems to be where individual ports are registered, there is an array of type "uart_8250_port" (http://lxr.linux.no/linux+v2.6.30/drivers/serial/8250.c#L2632) which holds data pertaining to a specific port, which is then registered with the serial core (http://lxr.linux.no/linux+v2.6.30/drivers/serial/8250.c#L3116).
Martyn
appreciate your kind help,
vichy
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