I386_VM86(2) | NetBSD System Calls Manual (i386) | I386_VM86(2) |
int
i386_vm86(struct vm86_struct *vmcp);
The kernel keeps a pointer to the context, and uses the tables stored at vmcp->int_byuser and vmcp->int21_byuser for fast virtual interrupt handling. If the n th bit is clear in the first of these arrays, then the kernel may directly emulate the real-mode x86 INT n instruction handling. If the n th bit is set, then the process is delivered a signal when an INT instruction is executed.
Since MS-DOS puts many DOS functions onto interrupt 21, it is handled specially: the k th bit in the vmcp->int21_byuser array is checked when INT 21 is requested and the ah register is k.
February 20, 1996 | NetBSD 5.99 |