README.wscons
author Ryan C. Gordon <icculus@icculus.org>
Mon, 12 Dec 2005 09:13:12 +0000
changeset 1199 2d6dc7de1145
parent 1187 19d8949b4584
permissions -rw-r--r--
From: Mike Frysinger <vapier@gentoo.org>
To: sdl@libsdl.org
Date: Sun, 11 Dec 2005 22:57:37 -0500
Subject: [SDL] exec stack in libsdl update

i posted back in September a patch to remove executable stacks:
http://www.devolution.com/pipermail/sdl/2005-September/070626.html

later in November, a similar patch was merged it seems:
http://www.libsdl.org/cgi/cvsweb.cgi/SDL12/src/hermes/mmx_main.asm

however, this lacks the additional output format checks that i posted in my
patch ... this isnt a problem if the hermes asm code is only ever used to
produce ELF objects, but if this is not true, then the additional checks in
my original patch will need to be merged
-mike
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==============================================================================
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Using the Simple DirectMedia Layer with OpenBSD/wscons
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==============================================================================
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The wscons SDL driver can be used to run SDL programs on OpenBSD
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without running X.  So far, the driver only runs on the Sharp Zaurus,
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but the driver is written to be easily extended for other machines.
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The main missing pieces are blitting routines for anything but 16 bit
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displays, and keycode maps for other keyboards.  Also, there is no
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support for hardware palettes.
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There is currently no mouse support.
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To compile SDL with support for wscons, use the
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"--enable-video-wscons" option when running configure.  I used the
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following command line:
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./configure --disable-oss --disable-ltdl --enable-pthread-sem \
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	    --disable-esd --disable-arts --disable-video-aalib  \
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	    --enable-openbsdaudio --enable-video-wscons \
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	    --prefix=/usr/local --sysconfdir=/etc
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Setting the console device to use
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=================================
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When starting an SDL program on a wscons console, the driver uses the
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current virtual terminal (usually /dev/ttyC0).  To force the driver to
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use a specific terminal device, set the environment variable
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SDL_WSCONSDEV:
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bash$ SDL_WSCONSDEV=/dev/ttyC1 ./some-sdl-program
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This is especially useful when starting an SDL program from a remote
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login prompt (which is great for development).  If you do this, and
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want to use keyboard input, you should avoid having some other program
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reading from the used virtual console (i.e., do not have a getty
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running).
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Rotating the display
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====================
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The display can be rotated by the wscons SDL driver.  This is useful
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for the Sharp Zaurus, since the display hardware is wired so that it
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is correctly rotated only when the display is folded into "PDA mode."
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When using the Zaurus in "normal," or "keyboard" mode, the hardware
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screen is rotated 90 degrees anti-clockwise.
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To let the wscons SDL driver rotate the screen, set the environment
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variable SDL_VIDEO_WSCONS_ROTATION to "CW", "CCW", or "UD", for
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clockwise, counter clockwise, and upside-down rotation respectively.
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"CW" makes the screen appear correct on a Sharp Zaurus SL-C3100.
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When using rotation in the driver, a "shadow" frame buffer is used to
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hold the intermediary display, before blitting it to the actual
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hardware frame buffer.  This slows down performance a bit.
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For completeness, the rotation "NONE" can be specified to use a shadow
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frame buffer without actually rotating.  Unsetting
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SDL_VIDEO_WSCONS_ROTATION, or setting it to '' turns off the shadow
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frame buffer for maximum performance.
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Running MAME
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============
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Since my main motivation for writing the driver was playing MAME on
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the Zaurus, I'll give a few hints:
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XMame compiles just fine under OpenBSD.
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I'm not sure this is strictly necessary, but set
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MY_CPU = arm
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in makefile.unix, and
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CFLAGS.arm = -DLSB_FIRST -DALIGN_INTS -DALIGN_SHORTS
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in src/unix/unix.max
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to be sure.
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The latest XMame (0.101 at this writing) is a very large program.
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Either tinker with the make files to compile a version without support
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for all drivers, or, get an older version of XMame.  My recommendation
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would be 0.37b16.
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When running MAME, DO NOT SET SDL_VIDEO_WSCONS_ROTATION!  Performace
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is MUCH better without this, and it is COMPLETELY UNNECESSARY, since
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MAME can rotate the picture itself while drawing, and does so MUCH
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FASTER.
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Use the Xmame command line option "-ror" to rotate the picture to the
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right.
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Acknowledgments
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===============
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I studied the wsfb driver for XFree86/Xorg quite a bit before writing
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this, so there ought to be some similarities.
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--
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Staffan Ulfberg <staffan@ulfberg.se>