Messages in this thread Patch in this message | | | Date | Tue, 26 Oct 1999 10:57:27 -0700 (MST) | From | Jesse Off <> | Subject | patch for lockup on bootup on certain embedded systems |
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The company I work for, NewMonics, does a lot of work on embedded systems and we've recently ported our product (a lightweight realtime Java virtual machine) to Linux. On some of the embedded systems/PLC's we work with (specifically, those based on the AMD Elan SC310 and SC300 386 microcontrollers) Linux fails to boot because the keyboard controller is not there to set the A20 bit. These machines are headless, keyboardless, and diskless (except for a small PCMCIA flash card). With the following patch, we were able to get our virtual machine running on Linux under this hardware via a serial port console.
--- setup.S Mon Aug 9 12:04:38 1999 +++ setup.S.patched Tue Oct 26 10:50:36 1999 @@ -553,6 +553,15 @@ out #0x60,al call empty_8042 +! The AMD 386 Elan SC300 and SC310 microcontrollers which +! are used in some embedded systems don't have +! a keyboard controller; we have to do things different on +! these chips. Jesse Off, NewMonics, Inc. <joff@newmonics.com> + + mov al,#0x2 ! GATEA20 functionality is acheived + out #0x92, al ! via port 0x92, bit 1. + + ! wait until a20 really *is* enabled; it can take a fair amount of ! time on certain systems; Toshiba Tecras are known to have this ! problem. The memory location used here is the int 0x1f vector,
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