English Amiga Board

Go Back   English Amiga Board > Support > support.WinUAE

Thread Tools
Old 04 April 2012, 14:30   #1
Registered User
Join Date: Apr 2005
Location: digital hell, Germany, after 1984, but worse
Posts: 3,095
Exclamation Very old JIT direct bug: 512 kB Chip reported as 1MB

There seems to be a very old bug with 512 kByte ChipMem which appears as 1MByte ChipMem instead to the Amiga OS (3.1) and leads to crashes, and this only happens with the JIT enabled and if running in "Direct" mode. Once the JIT has been disabled or switched to "Indirect" mode this issue never happens again until you restart WinUAE completely.

However, this is only a small bug, not very important for me, but by reporting this little issue here I would also like to take the chance to say THANK YOU to Toni for all the excellent work he is still doing to improve WinUAE constantly.

Update1: Added a comparison between JIT Direct (red) and Indirect (yellow) in the winuaelog.txt

Update2: This bug was introduced with WinUAE 1.0. The readme.txt of WinUAE 1.0 contains this note in its list of changes:

- improved JIT direct access memory area allocation (fixes JIT
direct mode problems with some Pentium 4 or NForce 3/4 boards)
Attached Thumbnails
Click image for larger version

Name:	512kB_ChipMemBug.png
Views:	276
Size:	44.6 KB
ID:	31172   Click image for larger version

Name:	JitDirect-IndirectCompare.png
Views:	2564
Size:	23.1 KB
ID:	31173  
Attached Files
File Type: txt winuaelog.txt (5.8 KB, 171 views)
File Type: txt winuaebootlog.txt (12.1 KB, 156 views)
File Type: uae FakedChipMem.uae (13.4 KB, 167 views)

Last edited by PeterK; 04 April 2012 at 17:13.
PeterK is offline  
Old 04 April 2012, 17:40   #2
Toni Wilen
WinUAE developer
Join Date: Aug 2001
Location: Hämeenlinna/Finland
Age: 47
Posts: 25,367
I think it was this one:

- DMA accesses to upper 512kb of chip RAM with only 512k chip RAM
and 1MB Agnus installed don't map to low 512kb like CPU accesses do.

JIT direct still "see" this hidden 512k region because JIT direct ignores all memory banks and mask.

Will be fixed in next beta.
Toni Wilen is offline  
Old 04 April 2012, 21:08   #3
Registered User
Join Date: Apr 2005
Location: digital hell, Germany, after 1984, but worse
Posts: 3,095
Many thanks for this quick response. It works as it should, but I didn't expect anything else.

Last edited by PeterK; 06 April 2012 at 12:08.
PeterK is offline  

Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
Thread Tools

Similar Threads
Thread Thread Starter Forum Replies Last Post
A500 - 6A, 1MB chip + some fast Chain support.Hardware 97 06 November 2012 13:41
020 + JIT bug? smoorke support.WinUAE 2 16 July 2009 20:52
Gui bug - JIT + 24 Bit (?) rsn8887 support.WinUAE 3 29 October 2008 16:01
a4000/40, 1mb chip ?! aix support.Hardware 9 08 July 2006 17:35
Copper/jit bug workarround Leandro support.WinUAE 11 17 September 2002 09:21

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump

All times are GMT +2. The time now is 00:34.

Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2022, vBulletin Solutions Inc.
Page generated in 0.09808 seconds with 16 queries