On Sat, Nov 14, 2009 at 04:38:22PM +0100, Robert Millan wrote: > > Following code can check A20: > > *((volatile grub_uint8_t *) 0x200000) = 0; > > *((volatile grub_uint8_t *) 0x300000) = 1; > > if (*((volatile grub_uint8_t *) 0x200000)) > > grub_printf ("Expect bugs\n"); > > else > > grub_printf ("You're safe\n"); > > Yeah, in fact we have gate_a20_check_state() to check for this, but only > in i386-pc. > > I find it surprising that i386-qemu works at all without it. I guess it > only works because the high mem area that would overlap with our code in > 0x8200 is never used. > > I'll look into this...
It appears that QEMU hardware already starts with A20 enabled. I suppose it's bochsbios who disables it. In any case, I made my vbe-on-coreboot branch enable it. Unfortunately, this wasn't the cause that prevented vbetest/vbeinfo from working :-/ -- Robert Millan The DRM opt-in fallacy: "Your data belongs to us. We will decide when (and how) you may access your data; but nobody's threatening your freedom: we still allow you to remove your data and not access it at all." _______________________________________________ Grub-devel mailing list Grub-devel@gnu.org http://lists.gnu.org/mailman/listinfo/grub-devel