Does modern PC video hardware support VGA text mode in HW, or does the BIOS emulate it (with System Management Mode)?
问题 What really happens on modern PC hardware booted in 16-bit legacy BIOS MBR mode when you store a byte such as '1' (0x31) into the VGA text (mode 03) framebuffer at physical linear address B8000 ? How slow is a mov [es:di], eax store with the MTRR for that region set to UC? (Experimental testing on one Kaby Lake iGPU laptop indicates that clflushopt on WC was roughly the same speed as UC for VGA memory. But without clflushopt, mov stores to WC memory never leave the CPU and don't update the