Reply 60 of 71, by mbbrutman
When you say upper memory, what exactly do you mean? The space above 640K and below 1MB, or the 64K space above 1MB?
mTCP doesn't really care about upper memory; it provides the buffers that the packet driver is going to use from the space allocated for the application, which is in conventional memory. Below 1MB nothing (mTCP or the packet driver) should have a problem. Using the 64KB above 1MB might be a problem if something isn't handling the segmented pointers correct, but mTCP doesn't hand out addresses up there so it's probably not on the mTCP side.
(mTCP uses a software interrupt to communicate with the packet driver and provides pointers to buffers for the packet drive to use. mTCP will scan for a magic string in the packet driver area, so if DHCP started running and was waiting for a DHCP acknowledgement then it found the packet driver. But otherwise, it will never touch memory that the mTCP application itself didn't allocate, and that's always below 1MB.)