Re: Moving Com1/2 from interrupts 4/3 via the IO-APIC ?

David Woodhouse (Dave@imladris.demon.co.uk)
Wed, 20 May 1998 21:25:32 +0200

> On Wed, 20 May 1998, Steven Ireland wrote:
>
> #Hi All,
> #
> #Would it be possible on PC's with IO-APIC's to relocate the interrupts used
> #by the motherboard COM ports to the 16+ range and free irq 3 & 4 for use on
> #the ISA bus ?
>
> Should be. Here's what you'll need to do to linux/drivers/char/serial.c

<...>

> struct async_struct rs_table[] = {
> /* UART CLK PORT IRQ FLAGS */
> { 0, BASE_BAUD, 0x3F8, 17, STD_COM_FLAGS }, /* ttyS0 */
> { 0, BASE_BAUD, 0x2F8, 18, STD_COM_FLAGS }, /* ttyS1 */
> { 0, BASE_BAUD, 0x3E8, 4, STD_COM_FLAGS }, /* ttyS2 */
> { 0, BASE_BAUD, 0x2E8, 3, STD_COM4_FLAGS }, /* ttyS3 */
>
> Where 17 and 18 are the IRQs you want to use. :)

Er, yeah - that's the easy bit. Now how about telling the chipset that we
actually want those IRQs delivered from the hardware to the right place?

---- ---- ----
David Woodhouse, Robinson College, CB3 9AN, England. (+44) 0976 658355
Dave@imladris.demon.co.uk http://www.imladris.demon.co.uk
finger pgp@dwmw2.robinson.cam.ac.uk for PGP key.

-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.rutgers.edu