At 01:49 AM 8/13/2006 +0200, Japheth wrote: >Not a severe problem (IMO it's more like a feature), but the A20 line >switching will only work if an UMB handler has been installed. There are some >constellation where this is not true, and then the A20 gate is unhandled by >Emm386.
Don't see exactly where this would happen in a supported configuration, since EMM386 requires HIMEM/XMS manager presence and handles UMB's internally. Nonstandard, unsupported configurations, well, can always plan for that later. >There is also still no option to deactivate the A20 thing. I don't like it. Adding new options was expressly addressed in the hard freeze announcement: just don't do it. In fact, we already stretched the letter of the hard freeze all to hell by adding the build subsystem and server/host stack change for an existing nondefault option. The justifications are that the server stack change is a potential fatal fault waiting to happen, it simply wasn't triggered for the test programs under standard conditions, and that the build subsystem didn't touch existing code. Still, recent changes were pushing the FreeDOS freeze rules by a lot. I anticipate an A20 control option being first in the EMM386 3.00 feature space, depending on who's involved in that. >A possible problem, but most likely also minor, if at all: the emulation of >int 15h, ax=87h modifies PTEs under certain conditions, but I couldn't find a >TLB flush done afterwards. That probably would have been if it had been known prior to 2.23, although I'm not sure it's a problem. You would need a case where there's MMIO access on multiple pages outside normal memory address range to use and reuse the scratch entries differently while within the (very small) TLB cache space. And you have to avoid any intervening task switch or explicit CR3 flush. I'd have to think harder about how you could get a bad TLB entry; maybe it's possible. Even if it is, doesn't seem terribly likely, more a small loophole that can be closed in 3.x. ------------------------------------------------------------------------- Using Tomcat but need to do more? Need to support web services, security? Get stuff done quickly with pre-integrated technology to make your job easier Download IBM WebSphere Application Server v.1.0.1 based on Apache Geronimo http://sel.as-us.falkag.net/sel?cmd=lnk&kid=120709&bid=263057&dat=121642 _______________________________________________ Freedos-devel mailing list Freedos-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/freedos-devel
