AMD Elan Patch for Linux

Intro

This patch cleans up some problems of the AMD Elan Processors (tested on a DIL/Net-PC). It concentrates several patches which have been discussed on the Linux Kernel Mailing List.

Fixes

Clock Frequency: A normal PC has a basic frequency for the system timer 0 of 1.19318 MHz, whereas the Elans have 1.1892 MHz. Without the patch the clock is wrong. (Jason Sodergren)

Starting with 2.4.18-pre7 this patch is part of the official kernel.

Serial Bug: The on-chip serial interface has a nasty bug: the UART_LSR_THRE bit is delayed one bit clock after the interrupt line is asserted, i.e. if the serial port is running at 1200 bps, and the tranmitter becomes empty and causes an interupt, the interrupt is signalled about a millisecond (1/1200second) _before_ the THRE bit is set. This means that when the interrupt handler is entered after the interrupt, the THRE bit is still clear, the handler believes that there is nothing to be done and returns. (Christer Weinigel) (Juergen Beisert)

A20 Gate: For the activation of the A20 gate register 0xEE is read instead of the "normal" code; the latest versions of the patch use register 0x92 which also works on SC520. Otherwise the Linux standard bootcode doesn't work - the reason for this behaviour is unclear. (Christer Weinigel, Juergen Beisert)

Starting with 2.4.18-pre7 this patch is part of the official kernel.

Patch

To use the patch select "Elan" as your processor type while configuring the kernel.

elan-patch-2.4.13.1 (2001/12/31)	[changelog]
elan-patch-2.4.14.1 (2001/12/31)	[changelog]
elan-patch-2.4.17.1 (2001/12/31) elan-patch-2.4.17.2 (2001/12/31) elan-patch-2.4.17.3 (2002/01/02)	[changelog] [changelog] [changelog]
elan-patch-2.4.18.1 (2002/02/26)	[changelog]

For outdated versions of the patch against -pre and -rc kernels see the archive.