Carl-Daniel Hailfinger wrote:
Yes, but the problem is that the CAR area can't be saved before enabling CAR. That means we have to reserve the memory. Let me summarize the current black list:
- 0x00000-0x9FFFF is low 640 kB. May break bootloaders and 16-bit OS.
- 0xA0000-0xAFFFF is VGA graphics memory mapped area.
- 0xB0000-0xB7FFF is ancient monochrome memmapped, but may still be
decoded by newer VGA cards.
- 0xB8000-0xBFFFF is VGA text mode memory mapped area.
- 0xC0000-???? is VGA ROM location.
- 0xF0000-0xFFFFF is used by SeaBIOS.
IMO, the first choice would be 0xC4000-0xCFFFF (if VGA ROMs are 16 kB or smaller). 0xE0000-0xEFFFF would be the next possibility. If we can verify that bootloaders and operating systems can handle a reserved area below 0x9FFFF, that might be a viable choice as well.
Late to this discussion but here are my $.02.
Most VBIOS may truncate themselves to be smaller after init but the initial image size is 32K or larger these days.
E0000 is the normal location for BIOS expansion. I recommend allocating from EFFFF down and leave room at the bottom for more expansion ROMs.
Marc