Date: Mon, 17 Oct 2005 20:09:03 -0400 From: Mark Schreiber <mark7@alumni.cmu.edu> To: ryan@clutteredmind.org Subject: [PATCH]SDL mprotect() crash fix (I'm going to throw this patch your way at the suggestion of #SDL -- for some reason, I had some difficulty sending it to the main list last time, and I go bonkers subscribing to send each email or patch...) Currently, when I run SDL applications as non-root using SDL_VIDEODRIVER=dga, the fbdev fallback mprotect()s read/write the proper size of mmapped /dev/fb0 (7.5MB), but on framebuffer release mprotect()s read-only the range by the entire size of my video memory (128MB), which causes a segfault: #0 0x002a9a27 in ?? () from /lib/libc.so.6 #1 0x04a63eb6 in SDL_XDGAUnmapFramebuffer (screen=3D0) at XF86DGA2.c:978 #2 0x04a63efc in SDL_XDGACloseFramebuffer (dpy=3D0x9d3f008, screen=3D0) at XF86DGA2.c:268 #3 0x04a68b57 in DGA_Available () at SDL_dgavideo.c:98 #4 0x04a53677 in SDL_VideoInit (driver_name=3D0xbfb0bfc7 "dga", flags=3D0) at SDL_video.c:180 #5 0x04a2613f in SDL_InitSubSystem (flags=3D32) at SDL.c:74 #6 0x04a2617c in SDL_Init (flags=3D32) at SDL.c:166 #7 0x08049722 in main (argc=3D1, argv=3D0x0) at testwin.c:32 This is SDL 1.2.8 on Fedora Core 4, radeon driver for a Radeon 9250, xorg-x11-6.8.2-37. I've attached a one-line patch against SDL CVS that updates the size of the framebuffer at framebuffer map time so that the mprotect() on unmap will be the same size. I'm not sure if this is the best approach (i.e. one might want to retain the original value), but it does make my SDL applications work without segfaulting. -- Best of luck, Mark Schreiber

Project files for embedded Visual C++ 4.0 can be found in VisualCE.zip

NOTE:
There are several SDL features not available in the WinCE port of SDL.

- DirectX is not yet available
- Semaphores are not available
- Joystick support is not available
- CD-ROM control is not available

In addition, there are several features that run in "degraded" mode:

Preprocessor Symbol		Effect
===================		=================================

SDL_systimer.c:
USE_GETTICKCOUNT		Less accurate values for SDL time functions
USE_SETTIMER			Use only a single marginally accurate timer

SDL_syswm.c:
DISABLE_ICON_SUPPORT		Can't set the runtime window icon

SDL_sysmouse.c:
USE_STATIC_CURSOR		Only the arrow cursor is available

SDL_sysevents.c:
NO_GETKEYBOARDSTATE		Can't get modifier state on keyboard focus

SDL_dibevents.c:
NO_GETKEYBOARDSTATE		Very limited keycode translation

SDL_dibvideo.c:
NO_GETDIBITS			Can't distinguish between 15 bpp and 16 bpp
NO_CHANGEDISPLAYSETTINGS	No fullscreen support
NO_GAMMA_SUPPORT		Gamma correction not available