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53 lines
2.1 KiB
Plaintext
53 lines
2.1 KiB
Plaintext
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From: "Paolo Marini" <paolom@prisma-eng.it>
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Subject: Etherboot on bare metal
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Date: Tue, 10 Apr 2001 23:19:19 +0200
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Organization: Prisma Engineering srl
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Hi Ken,
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I have ported Etherboot on an embedded, biosless platform and would like
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to contribute the code.
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Essentially, the hardware I was running Etherboot is a Pentium based
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embedded system, with an Intel Chipset, *but* without serial, VGA,
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keyboard etc., only an 82559 Intel (custom) Ethernet controller (I debug
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it with the etheral Ethernet packet analyser and an emulator).
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What I did was:
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a.. integrate the init.s file within the firmware, with GDT
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(re)initialisation (a simple and single entry point taking control of
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the boot process)
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b.. provide some stupid BIOS stubs in order to let the OS boot and
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still belive that an INT10 call goes to the BIOS
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c.. provide some basic functions to Etherboot, like timer (I used the
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Pentium TSC internal counter)
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d.. hardwire in the code information about the RAM size
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The BIOS stubs are enough to boot Linux, pSOS and QNX with bootp. QNX is
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somewhat difficult to load, because the i82559 driver tries to find the
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component using the BIOS32 calls, so I had to patch it.
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what i I got from the original firmware is the PCI initialisation and
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resource (I/O, interrupts, memory) allocation.
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I send you what I changed, that is, the initialisation code and the
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misc.c file containing the timer, and the makefile (I don't remember
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exactly the options I used to compile all).
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Of course, it is only a good starting point for anyone wanting to
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implement a bootp client on a biosless platform; some integration work
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still needs to be done.
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Ciao
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Paolo
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And in a subsequent email:
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I worked with version 4.6.12, but the real modifications involve the
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init.S file, which I think is quite sstable between releases. I forgot
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to say that my entry point (symbol _start in init.s) assumes the
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processor is already in protected mode.
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[The only difference between main.c and misc.c from those in Etherboot
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4.6.12 seems to be the deletion of eth_reset(). This may be of use to
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others trying to make these changes work on more recent releases. Ken]
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