Robert Millan wrote: > I'm wondering how come the i386-qemu port works if none of its > initialization code takes into account gate A20. Does this > mean it's supposed to be already disabled in initial CPU state, > and only enabled by BIOS? > > Or maybe the code only works by chance and would break unexpectedly > in specific situations? > > Without disabling A20 even and odd mibibytes will be squashed together. 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");
-- Regards Vladimir 'phcoder' Serbinenko
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