John J. Binder asks:
I'm trying to figure out how to run irq 0x10 from gcc so as to interact with the video card directly.
Michael K. Johnson replies:
If you had read the KHG, you would have discovered that you can only access interrupts from kernel code, not from user-level code.
May I take it then that it is possible from kernel code?
I have toured the KHG and found no mention of calling software interrupts. Receiving hardware interrupts is of course covered, but this is different.
It would be nice to be able to write a device driver for VBE2 display devices. This would give the application programmer access to the display, similarly to svgalib but with higher resolutions and more colours. It would also allow an X server to be written for those devices which are currently unsupported, including NeoMagic graphics adapters found in many laptops (including mine - hence my interest in this subject).
The VBE2 interface requires one to call `int 0x10' with, among other things, the real-mode address of a block of memory in ES:DI.
An alternative to the device driver would be to implement a system call like int86x() to emulate software interrupts in real mode and export the address mapping functions to user level code.