At 01:59 PM 3/19/2005 +0100, Eric Auer wrote:
> Many illegal memory accesses in programs which won't fail under HIMEM will
> fail with EMM386 loaded. EMM386 does not allow memory reads/writes outside
> of the actual PC memory range due to protected mode /V86...
You forget that the MEMCHECK switch for your EMM386 fixes this, by allowing int 15.87 memory access to anywhere, even non-RAM space :-).
No, I just think indiscriminate use of MEMCHECK to mask program bugs is generally a bad idea unless one cannot fix or work-around the problem.
Other EMM386 things from the last 12 hours:
> Certainly true that VCPI provides discrete allocations in 4K units... Yes, in fact, the int 67.de04 call always allocates exactly ONE page! The current implementation scans a whole array of "4k page used" bits, avoiding all "completely used" and "completely free" 16k aligned 16k pages, to keep as many EMS pages useable as possible. While being very nice to EMS performance that way, you get quite bad VCPI performance.
Well, since it's all being rewritten it's a moot point.
Blaming the allocator for slow VCPI performance is pretty much BS, however. They still teach the merits of algorithmic improvement over code optimization in school and programming books, right? Although it's much more fun, I'm sure, to blame the implementation code rather than the underlying concepts of caching and memory management.
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