Linux Config

Linux Config

In kernel menuconfig, you should usually select either jtag uart or serial uart for console device (but not both).

You should use exactly only one of them for console.

Device Drivers ---> Character devices ---> Serial drivers --->

[ ] 8250/16550 and compatible serial support

*** Non-8250 serial port support ***

[*] Altera JTAG UART support

[*] Altera JTAG UART console support # if you use a USB (Blaster) cable on a nios2-terminal

[ ] Bypass output when no connection # go without a nios2-terminal

[*] Altera UART support

(4) Maximum number of Altera UART ports

(115200) Default baudrate for Altera UART ports

[ ] Altera UART console support # if you use a 9-pin RS-232C cable on a terminal emulator such as minicom or ckermit or hyperterminal

The jtag uart will freeze if there is no nios2-terminal connected. You can keep the system working without a jtag connection, by turn on

[*] Bypass output when no connection

The jtag uart will connect again when there is a nios2-terminal on jtag connection.

The init prog will start a shell on the console device. So if you want to run app which use uart, then you should not enable uart console.

File mode mapping on initramfs

If your user id and group id on Linux are not 500, change these to your id instead. This will be used to map user file/dir ownership to root in initramfs.

General setup --> (for new kernels)

OR

Device Drivers --> Block devices --> (for 2.6.11-uc0)

(500) User ID to map to 0 (user root)

(500) Group ID to map to 0 (group root)

Large kernel image

If your kernel image is large, you will need to change this config.

Processor type and features-->(0x00500000) Link address offset for booting.

The zImage load address is ( your sdram base address + link address offset ). The boot loader will uncompress the code to the beginning of sdram. If the uncompressed code is bigger than the default 5M, the two area will overlap and corrupt. The compressed image offset should be adjusted to a higher value when the kernel image is big, eg, large files in romfs dir. You can change this value to about 2/3 of the size of your sdram, eg, 20M out fo 32M. I suggest 2/3 because the gzip compression ratio is about 1:2. The zImage boot loader does not relocate/move itself.

If you can not find Platform board support of your board in Processor features, just use the default.

Serial Uart on NEEK

The serial uart TXD pin is a dual purpose pin, you have to change the pin usage,

Assignements -> Device Settings -> Device -> Device and Pin Options -> Dual-Purpose Pins -> nCEO -> Use as regular IO

input HC_UART_RXD;

output HC_UART_TXD;

.rxd_to_the_uart (HC_UART_RXD),

.txd_from_the_uart (HC_UART_TXD),