I did a little more playing around, and found out that using this method doesn't worked in x86 protected mode. I can't stick code in before I switch to protected mode and it works. Any clues on doing vga programming in protected mode. I know it uses the 6845 chip for this, but can't seem to find any sample code. On Friday 27 September 2002 9:57 am, John Tyner wrote: > I can't speak to that what you're doing is actually correct, however > because you make three separate asm calls, it is possible that the > compiler is doing something strange in between. You should use: > > asm volatile ( > "movb $0x00, %ah\n" > "movb $0x13, %al\n" > "int $0x10\n" > ); > > Also note that you are destroying the current value in the ax register > without telling the compiler. Check out http://www.linuxassembly.org/ for > more information about inline assembly. > > On Fri, 27 Sep 2002, Tom Bradley wrote: > > I am trying to do a simple vga(320x200x256) driver but am having troubles > > switching the video mode. I am using: > > asm volatile("movb $0x00, %ah;"); > > asm volatile("movb $0x13, %al;"); > > asm volatile("int $0x10;"); > > which several websites and books are saying is all that is needed to > > switch modes. However this locks up my machine. What am I doing wrong? > > > > > > -- > > Kernelnewbies: Help each other learn about the Linux kernel. > > Archive: http://mail.nl.linux.org/kernelnewbies/ > > FAQ: http://kernelnewbies.org/faq/ -- Kernelnewbies: Help each other learn about the Linux kernel. Archive: http://mail.nl.linux.org/kernelnewbies/ FAQ: http://kernelnewbies.org/faq/
