Glad you got it to work then, all the legacy code still left must make it hard to change anything without breaking something else.
On Thu, Apr 12, 2012 at 8:24 AM, Stas Sergeev <s...@list.ru> wrote: > Hello. > > I needed to run some commercial DOS-based multitasking > environment recently, which doesn't work under dosbox. > It implements the memory context switching by the use of > EMS. dosemu doesn't support this, but it was easy to implement, > so the patch is attached. > There is still a problem with this patch that I'd like to address > to make sure the multitasker will work reliably. > It defeats the meaning of IS_GENERIC_LOWMEM_ADDR(). > In the patch I just removed it entirely to make things a go, > otherwise the multitasker just crashes here and there, but > my concern is that it will crash sooner or later again, because, > with the 0-based conv memory, dosemu will attempt to write > to zero page. > I can see the following solutions to this: > 1. Make IS_GENERIC_LOWMEM_ADDR() end at 0x40000, > rather than at 0xa0000. This will work because in my patch > I made it so the addresses below 0x40000 are never mappable, > but who knows if some other multitasker will require also this. > 2. Introduce the lowmem_alias maintained by mapping.c. > Actually, when I introduced lowmem_base, the intention was > only to provide it to the different "mappers", like EMS/HMA/DPMI. > Only much later someone started to use it as an alias for zero-page, > but maybe this should not have been done. > 3. Make a fully functional dosaddr_to_unixaddr(), not just > a quick hack it currently is. It should use the proper reverse-mapping > maintained by mapping.c, instead of relying on a "map_char". > > I think the most "correct" approach is 3, while the simplest is 1. > I personally wouldn't go for 2, but the changelog suggests that > 2 was attempted at times already. > Then, if this is fixed, I think all the uses of LOWMEM() should > be killed, except those intended initially: for the use by the mappers. > No one, except "mappers", should use LOWMEM(). Fortunately, > the uses of LOWMEM() are already very few in the code. > > I cannot understand what lowmemp() does. It seems to take the > dos pointer, but, for the "side-mapped" areas, it returns that > pointer directly, both without adjusting it to mem_base, and > without looking up the mapping source. How does this work? > > My patch also touches dosdebug: that's a hack too, but > otherwise dosdebug just randomly exits for me. What's the > use of searching for 1 in the read buffer? > > Also, there seems to be the e_invalidate() calls spread around > the code. I haven't added them to my patch because I don't > think its the right thing to do, but again, this may introduce > the instability. We already have the macros to access the DOS > memory, so why was it necessary to litter with the e_invalidate() > calls, forcing everyone to include "cpu-emu.h"? > > But the good thing is that the aforementioned multitasker > works under (patched) dosemu even on x86_64. I am surprised > with how mature the CPU emulator is; it was barely usable > the last time I looked. :) I think KVM also has the CPU emulator > builtin. Was this considered as the speedup? > > ------------------------------------------------------------------------------ > For Developers, A Lot Can Happen In A Second. > Boundary is the first to Know...and Tell You. > Monitor Your Applications in Ultra-Fine Resolution. Try it FREE! > http://p.sf.net/sfu/Boundary-d2dvs2 > _______________________________________________ > Dosemu-devel mailing list > Dosemu-devel@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/dosemu-devel > ------------------------------------------------------------------------------ For Developers, A Lot Can Happen In A Second. Boundary is the first to Know...and Tell You. Monitor Your Applications in Ultra-Fine Resolution. Try it FREE! http://p.sf.net/sfu/Boundary-d2dvs2 _______________________________________________ Dosemu-devel mailing list Dosemu-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/dosemu-devel
