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Re: Finding bugs in 8086-80186 emulation core?

Posted on 2017-08-02, 20:27

Currently converting much of the Ev vs Gv logic to use the lookup tables instead(only up to 80186 so far), but for some still unknown reason, the Turbo XT BIOS crashes on the VGA, according to it's beep codes(not crashing 2 commits back). I'm also considering converting the protection/interrupt …

Re: x86 TLB vs protection?

Posted on 2017-07-31, 13:58

I've modified the TLB lookup from the MMU to not retrieve non-dirty entries during writes, now handling dirty frames and their writeback into memory correctly: https://bitbucket.org/superfury/unipcemu/src/ … ing.c?at=master

Re: x86 TLB vs protection?

Posted on 2017-07-30, 19:19

What I mean, is that the TLB is looked up with the Tag consisting of R/W being whether an access is a read or a write. The Tag's Dirty bit is looked up as 1(during writes only) and 0 always. The Tag's U/S bit is looked up as CPL being 3 or not. Thus, the method described in my last post will make …

Re: Finding bugs in 8086-80186 emulation core?

Posted on 2017-07-30, 17:51

Just tried installing Windows 3.0 with the CGA emulation and NEC V30 XT(80186) configuration. Windows 3.0 setup continues past given point, until it gets to disk 4, after which the keyboard becomes unresponsive for some unknown reason. Restarting win.com from the command line makes it continue at …

Re: Finding bugs in 8086-80386 emulation core?

Posted on 2017-07-29, 01:26

Trying to find a simple testsuite for the 80386 leads me to this: http://marc.info/?l=bochs-dev&m=124236420804902 But, unfortunately, it seems to contain stuff for an FPU and/or newer unsupported CPUs as well. Currently only up to 80486SX is implemented(Pentium would be tough, seeing as it has …

Re: Finding bugs in 8086-80386 emulation core?

Posted on 2017-07-28, 23:04

I've just tried copying the Windows 3.0 setup files(valid files) from CD-ROM ISO image using the Compaq Deskpro 386 emulation, then installing Windows 3.0 on the NEC V30 XT configuration. The AT drivers(himem.sys, vide-cdd.sys) abort loading because of the 'non-x86' CPU(although it might need a 32- …

Re: x86 TLB vs protection?

Posted on 2017-07-28, 19:36

Not exactly. When user mode accesses the TLB, it does a lookup with the user bit set to 1. That will fail, as it's never addes(as the protection bits cause a fault when it's first loaded, thus it cannot be in the TLB). So the TLB lookup fails in user mode(U bit being 1, which generates a tag that …

Re: UniPCemu emulator releases

Posted on 2017-07-28, 19:29

The latest UniPCemu release(PC and Android): https://www.dropbox.com/s/7kxdmolnkd321j9/UniPCemu_20170728_2101.zip?dl=0 Changelog: - Improved automatic direct plot(choosing between forced and disabled rendering mode automatically) on devices with static screens(like Android and PSP). - Made resuming …

Re: x86 TLB vs protection?

Posted on 2017-07-27, 23:35

So the sets are the big memory area spaces(0-1GB, 1-2GB, 2-3GB and 3-4GB linear memory). Each of those areas(sets) owns 8 entries to store and load entries(struct containing tag(consists of user(CPL being 3 or not), RW(access being a write or not) and linear 4KB block(bits 12-31 of the linear …

Re: ATAPI CD-ROM change disk?

Posted on 2017-07-27, 19:57

After some time, it continues(with huge delays between and after reads), but after that specific IRQ, it goes slowly instead of the usual fast(huge delays)? https://bitbucket.org/superfury/unipcemu/src/6dcccb60a80bb114539a10197e89dc38f0b04a0a/UniPCemu/hardware/ide.c?at=master Can anyone see what's …

Re: x86 TLB vs protection?

Posted on 2017-07-27, 11:10

Thinking about it, it's not too difficult. The only remaining problem for implementation is this: it says it's divided into four blocks(sets). How is the set to use with a memory address chosen? Is it bits 31-30? Or 13-12? Or something else entirely?

x86 TLB vs protection?

Posted on 2017-07-27, 01:01

I've been reading https://pdos.csail.mit.edu/6.828/2016/readings/i386/s10_06.htm This shows that the 80386 is using some four-way lookup TLB? How is this used on a 80386+? What do those four entries do? Does it contain protection data as well? So when a memory access is made(giving read/write, user/ …

Re: Finding bugs in 8086-80386 emulation core?

Posted on 2017-07-26, 12:28

This is a log of the entire FDC booting MS-DOS 5.0 with HIMEM.SYS, then failing on the remaining parts: Filename 406.jpg File size 40.65 KiB Views 358 views File comment Screen capture directly after the log. Filename debugger.log File size 369.52 KiB Downloads 16 downloads File comment Floppy disk …

Re: Finding bugs in 8086-80386 emulation core?

Posted on 2017-07-26, 12:03

I'm trying to get the FDC working properly again on the XT(with a 80386 without any waitstates for faster testing), but for some reason, my floppy disk boots fine, until it's past the HIMEM.SYS driver, after which the floppy disk controller goes awry for some reason? It says: Bad or missing VIDE-CDD …

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