On Wed, May 18, 2011 at 1:44 AM, Hornung, Michael <mhornung@xxxxxxxxxx> wrote:
>>> There is an UART (FPGA IP Core) in that system located at address 1900h using interrupt 3. In order to get Kernel messages at boot time,
>>> I changed file arch/x86/include/asm/serial.h as follows:
>>>
>>> - { 0, BASE_BAUD, 0x3F8, 4, STD_COM_FLAGS }, /* ttyS0 */ \
>>> + { 0, BASE_BAUD, 0x1900, 3, STD_COM_FLAGS }, /* ttyS0 */ \
>>>
>>> that is the only change I made to the kernel sources.
>
>> Is this UART connected via PCI? I don't think so, because I don't see
>> any I/O BARs that include 0x1900.
>
> The UART is connected via LPC bus.
Makes sense; that's a common way for attaching UARTs, and they are
normally described via ACPI. When you do that, I think it will show
up as ttyS4 (be sure you build with CONFIG_SERIAL_8250_PNP=y), so
you'll have to use "console=ttyS4" when you boot. ttyS0-ttyS3 are
taken by the hard-coded ports in serial.h, even though they may not
exist on your platform.
Bjorn
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