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$Id: misc.html,v 1.66 2006/12/30 13:30:51 debug Exp $ |
$Id: misc.html,v 1.67 2007/03/24 06:39:29 debug Exp $ |
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Copyright (C) 2003-2007 Anders Gavare. All rights reserved. |
Copyright (C) 2003-2007 Anders Gavare. All rights reserved. |
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developing firmware, using GXemul</a> |
developing firmware, using GXemul</a> |
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<li><a href="#compilercontruct">Using GXemul in compiler contruction courses</a> |
<li><a href="#compilercontruct">Using GXemul in compiler contruction courses</a> |
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<li><a href="#disk">How to start the emulator with a disk image</a> |
<li><a href="#disk">How to start the emulator with a disk image</a> |
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<li><a href="#tape_images">How to start the emulator with tape images</a> |
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<li><a href="#disk_overlays">How to use disk image overlays</a> |
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<li><a href="#filexfer">Transfering files to/from the guest OS</a> |
<li><a href="#filexfer">Transfering files to/from the guest OS</a> |
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<li><a href="#largeimages">How to extract large gzipped disk images</a> |
<li><a href="#largeimages">How to extract large gzipped disk images</a> |
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<li><a href="#userland">Running userland binaries</a> |
<li><a href="#userland">Running userland binaries</a> |
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</pre> |
</pre> |
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It is probably possible to use harddisks as well this way, but I would not |
It is probably possible to use harddisks as well this way, but I would not |
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recommend it. |
recommend it. |
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<p> |
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<p><br> |
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<a name="tape_images"></a> |
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<h3>How to start the emulator with tape images:</h3> |
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Using emulated tape drives is a bit more complicated than disks, because a |
Using emulated tape drives is a bit more complicated than disks, because a |
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tape can be made up of several "files" with space in between. The solution |
tape can be made up of several "files" with space in between. The solution |
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I have choosen is to have one file in the host's file system space for each |
I have choosen is to have one file in the host's file system space for each |
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on the command line. By changing what the symbolic name points to, |
on the command line. By changing what the symbolic name points to, |
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you can "switch tapes" without quiting and restarting the emulator. |
you can "switch tapes" without quiting and restarting the emulator. |
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<p> |
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<font color="#ff0000">Note: Tape support is most likely very buggy, |
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because it has not been tested much, and has probably also suffered |
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from bit-rot by now.</font> |
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<p><br> |
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<a name="disk_overlays"></a> |
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<h3>How to use disk image overlays:</h3> |
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This is most likely best understood by an example: |
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<p><ul> |
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<li>Install e.g. <a href="guestoses.html#netbsdcatsinstall">NetBSD/cats</a>. |
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You will end up with a disk image called |
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<tt>nbsd_cats.img</tt>. |
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<p> |
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<li>Running the following command will boot straight from the disk |
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image, with no overlay images:<pre> |
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<b>gxemul -XEcats -d nbsd_cats.img netbsd.aout-GENERIC.gz</b> |
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</pre> |
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<li>You may now create an overlay file, a corresponding map file, |
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and start the emulator with the overlay image connected to |
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the same (explicit) ID as the base disk image:<pre> |
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<b>touch overlay.img overlay.img.map |
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gxemul -XEcats -d 0:nbsd_cats.img -d V0:overlay.img netbsd.aout-GENERIC.gz</b> |
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</pre> |
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<li>Any changes to the filesystem you perform when using the overlay |
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will only be written to that overlay. For example, to perform |
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a "roll back", you can do the following:<pre> |
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<b>rm -f overlay.img overlay.img.map |
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touch overlay.img overlay.img.map</b> |
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</pre> |
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and then simply start the emulator again, with the newly created |
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overlay image. |
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</ul> |
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<p>It is also possible to add multiple overlays. In that case, writes |
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always go the the <i>last</i> added overlay. |
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<p>GXemul uses Unix' way of supporting files with "holes", |
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so even if <tt>ls -l overlay.img</tt> says that the overlay is several |
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gigabytes large, <tt>du overlay.img</tt> should reveal that only the |
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blocks that have actually been written to have been stored in the |
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overlay, e.g.:<pre> |
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<b>$ ls -l |
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.. |
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-rw-r--r-- 1 debug wheel 3072319488 Mar 24 11:59 nbsd_cats.img |
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-rw-r--r-- 1 debug wheel 2465354 Mar 24 11:44 netbsd.aout-GENERIC.gz |
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-rw-r--r-- 1 debug wheel 2930841600 Mar 24 14:02 overlay.img |
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-rw-r--r-- 1 debug wheel 715538 Mar 24 14:02 overlay.img.map |
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$ du overlay.img |
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864 overlay.img |
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</b> |
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</pre> |
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<p>The .map file is simply a raw bitmap telling which blocks of the |
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overlay file that are in use. |
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