/* int $0x10 is known to have bugs involving touching registers
it shouldn't. Be extra conservative... */
- asm volatile("pushal; int $0x10; popal"
+ asm volatile("pushal; pushw %%ds; int $0x10; popw %%ds; popal"
: : "b" (0x0007), "c" (0x0001), "a" (0x0e00|ch));
}
* int $0x10 is notorious for touching registers it shouldn't.
* gcc doesn't like %ebp being clobbered, so define it as a push/pop
* sequence here.
+ *
+ * A number of systems, including the original PC can clobber %bp in
+ * certain circumstances, like when scrolling. There exists at least
+ * one Trident video card which could clobber DS under a set of
+ * circumstances that we are unlikely to encounter (scrolling when
+ * using an extended graphics mode of more than 800x600 pixels), but
+ * it's cheap insurance to deal with that here.
*/
-#define INT10 "pushl %%ebp; int $0x10; popl %%ebp"
+#define INT10 "pushl %%ebp; pushw %%ds; int $0x10; popw %%ds; popl %%ebp"
/* Accessing VGA indexed registers */
static inline u8 in_idx(u16 port, u8 index)