On Mon, 14 Jan 2002, Bryan J. Smith wrote: ... > it says 153KB is being used for DOS, 623KB of 640KB is free. I > assume it is using both the A20/HIGH line for 64KB of that, and some > various UMB blocks outside of common BIOS/memory maps as well as the ...
DOSEMU uses (386) mapping techniques to make all this possible. These are provided by the Linux kernel, normally using /proc/self/mem for 2.2 kernels and older, and using IPC shared memory for 2.4 kernels. See the $_mapping documentation. So ... upon dosemu startup, what dosemu sees as address 0x000000-0x00FFFF (0:0-0:FFFF, 16 4k pages) is mapped to the same physical memory as 0x100000-0x10FFFF (FFFF:10-FFFF:FFFF(+11)). This trick is documented in Intel's 386 manual. Then upon either the right XMS driver call or the right keyboard controller port "out" instruction, DOSEMU maps these portions to different parts of physical memory. Where exactly this physical memory is, is not interesting from DOSEMU's perspective; this is all handled by the Linux kernel. Bart - To unsubscribe from this list: send the line "unsubscribe linux-msdos" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html
