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I've tested that it works in emulation. The only test left is the real deal my a Sega Master System.
99 lines
3.7 KiB
Plaintext
99 lines
3.7 KiB
Plaintext
# Assembling Collapse OS from within it
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This is where we tie lose ends, complete the circle, loop the
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loop: we assemble a new Collapse OS *entirely* from within
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Collapse OS.
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Build Collapse OS' from within Collapse OS is very similar to
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how we do it from the makefiles in /arch. If you take
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the time to look one, you'll see something that look like "cat
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xcomp.fs | $(STAGE)". That's the thing. Open "xcomp.fs" in a
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text editor and take a look at it. Some xcomp units are simple
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proxy to a block, which you'll find in the blk/ subfolder for
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this recipe.
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To assemble Collapse OS from within it, all you need to do is
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execute the content of this unit, minus the 2 lines of "spitting
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to port 2" at the end of the unit, which is a special signal for
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the stage binary.
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The rest can be executed on any Collapse OS system with enough
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memory. It will yield a binary in memory. To know the start/end
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offset of the binary, you'll type the same two commands at the
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end of xcomp.fs, but replace the "/MOD 2 PC! 2 PC!" words with
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".X". Then, write that binary between those offsets on your
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target media. That binary should be the exact same as what you
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get in "os.bin" when you run "make". You now have a new Collapse
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OS deployment.
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Is that it? Yes. But for your own enlightenment, let's look at
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the xcomp unit in more details. Full details are at
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doc/bootstrap.txt.
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The first part is configuration of your new system. When RAM
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starts, where RSP and PSP start, what ports to use for what
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device, etc. These configuration declarations are expected in
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the boot code and driver code.
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Then, we load the proper assembler and the cross compiler (xcomp
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for short), which we'll of course need for the task ahead.
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Then come xcomp overrides, which are needed for xcomp to be
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effective.
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At this point, we're about to begin spitting binary content,
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this will be our starting offset. "ORG" will soon be set to your
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current "H@".
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Then, we assemble the boot binary, drivers' native words, then
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inner core, close the binary with a hook word. We're finished
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with cross-compiling.
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We're at the offset that will be "CURRENT" on boot, so we update
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"LATEST".
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Then, we spit the init source code that will be interpreted on
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boot. And... that's it!
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# What to do on SDerr?
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If you self host from a machine with a SD card and you get
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"SDerr" in the middle of a LOAD operation, something went wrong
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with the SD card. The bad news is that it left your xcomp
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operation in an inconsistent state. The easiest thing to do it
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to restart the operation from scratch. Those error are not
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frequent unless hardware is faulty.
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# Cross-compiling directly to EEPROM
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If your target media is a RAM mappable media, you can save prec-
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ious RAM by cross-compiling Collapse OS directly to it. It req-
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uires special handling.
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You can begin the process in a regular manner, but right before
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you're about to assemble the boot code, take a pause.
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Up until now, you've been loading your cross compiling tools in
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RAM, now, you're about to write Collapse OS. So what you need
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to do is change HERE to the address of your EEPROM. Example:
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0x2000 HERE !
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If you need to activate special system overrides such as the
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one described in doc/hw/at28.txt, now is the time.
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Then, you can continue the process normally.
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# Verifying
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You can use "/tools/memdump" to dump the memory between your
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begin/end offsets so that you can compare against your reference
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stage 1. Before you do, you have to take yourself out of xcomp
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mode. First, run XCOFF to go back to your regular dict. Then,
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run "FORGET CODE" to undo the xcomp overrides you've added
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before. That will rewind HERE. You don't want that. Put HERE
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back to after your ending offset so that you don't overwrite
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your binary.
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Then, you can run "/tools/memdump".
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