Vision Systems VScom 200E PCIex Bedienungsanleitung PDF herunterladen (Seite 43)

5 Linux Driver

5.2.2 New Models

If the model of VScom PCI card is new to the driver, users add the program vscardcfg to their

init scripts. This program detects the cards and the assigned parameters. Since this program

knows about all VScom PCI cards, it also knows the required parameters for the setserial command

mentioned in section 5.1. Then it performs the same tasks as users would do when manually invoking

setserial. Especially the parameters ’port’, ’irq’, ’uart’ and ’baud_base’ are given according to the

model and conﬁguration.

5.3 Problems since Kernel 2.6

In Linux systems based on Kernel 2.4 or earlier the installation of VScom PCI cards has been quite

easy. This has changed since kernel 2.6 came out. Not because the driver ’serial’ was removed

or could no longer support PCI serial ports. This happened because some programmers invented

a limit to the maximum number of serial ports installed by driver ’serial’. And they selected a

default value ridiculously low (typically 4), which caused problems again and again. So over time

they have been forced to oﬀer several methods of bypassing this limit.

5.3.1 Compile a new Kernel

In early versions the driver ’serial’ required a conﬁguration with a new limit. Then it had to be

compiled with this limit. Since usually the driver is not loaded as a module, this required to compile

the kernel.

Following kernel compile settings have to be set

CONFIG_SERIAL_8250_NR_UARTS=32 Maximum number of 8250/16550

UARTs

CONFIG_SERIAL_8250_RUNTIME_UARTS=32 Number of 8250/16550 serial

ports to register at runtime

CONFIG_SERIAL_8250_EXTENDED=y Extended serial port options mark

CONFIG_SERIAL_8250_MANY_PORTS=y Support more than 4 legacy serial

ports

mark

CONFIG_SERIAL_8250_SHARE_IRQ=y Support for sharing serial

interrupts

mark

Table 13: Kernel Compile Options

Depending on your distribution there may be diﬀerent methods to deﬁne these parameters. Menu-

conﬁg should be a good option.

5.3.2 Kernel Start Parameters

Today the implementation of the limit is in a way which allows to raise the deﬁned value at boot

time. This is done via Kernel parameters. How this is done depends on the way you boot your

system. Following is one example to do the task in Ubuntu 8.10 on AMD64 with Grub as boot

loader, basically Debian should operate the same way. Other distributions or loaders may require

modiﬁcations.

July 2011 VScom Industrial Card User Manual 43

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Vision Systems VScom 200E PCIex Bedienungsanleitung Seite 43