ERROR: BUG: dosemu touched the protected video memory!!!

ERROR: BUG: dosemu touched the protected video memory!!!

[Julius Schwartzenberg]

Hi,
When I run a program such as Duke Nukem, Dosemu quits with the following 
error:
ERROR: BUG: dosemu touched the protected video memory!!!
ERROR: cpu exception in dosemu code outside of VM86()!
trapno: 0x0e  errorcode: 0x00000006  cr2: 0x000a7000
eip: 0x08092657  esp: 0xbffff290  eflags: 0x00200246
cs: 0x0023  ds: 0x002b  es: 0x002b  ss: 0x002b
Page fault: write instruction to linear address: 0x000a7000
CPU was in user mode
Exception was caused by non-available page
ERROR: leavedos() called from within a signal context!
It works fine when running with direct video access on a console.
Other software such as Windows for Workgroups 3.11 and MS Word 6 for 
Windows works without problems.
I tried it with Dosemu 1.2.0 RC1 and stable 2003. With both version 
King's Quest seems to give the same problem. Prince of Persia works with 
stable 2003, but I believe it didn't work with 1.2.0 RC1.
Am I doing something completely wrong or is this a bug?
Thanks in advance,
Julius

Re: ERROR: BUG: dosemu touched the protected video memory!!!

[Bart Oldeman]

On Fri, 9 Jan 2004, Julius Schwartzenberg wrote:

> When I run a program such as Duke Nukem, Dosemu quits with the following
> error:
> ERROR: BUG: dosemu touched the protected video memory!!!
> ERROR: cpu exception in dosemu code outside of VM86()!
> trapno: 0x0e  errorcode: 0x00000006  cr2: 0x000a7000
> eip: 0x08092657  esp: 0xbffff290  eflags: 0x00200246
> cs: 0x0023  ds: 0x002b  es: 0x002b  ss: 0x002b
> Page fault: write instruction to linear address: 0x000a7000
> CPU was in user mode
> Exception was caused by non-available page
> ERROR: leavedos() called from within a signal context!
> It works fine when running with direct video access on a console.

This can be tricky depending on where dosemu is. One such instance was
solved fairly recently. Can you check where 0x8092657 (the value behind
eip:) is in bin/dosemu.map or by using gdb?

Were you talking about duke nukem 3d or some earlier duke?

> I tried it with Dosemu 1.2.0 RC1 and stable 2003.

The "DoSEMU stable 2003" you saw is a joke (witness DoS = denial of
service) -- it should have been called "cvs head 31 Dec 2003". Anyway I
got tired of him so it no longer exists.

Bart

Re: ERROR: BUG: dosemu touched the protected video memory!!!

[Julius Schwartzenberg]

Bart Oldeman schreef:

>This can be tricky depending on where dosemu is. One such instance was
>solved fairly recently. Can you check where 0x8092657 (the value behind
>eip:) is in bin/dosemu.map or by using gdb?
>
>Were you talking about duke nukem 3d or some earlier duke?
>  
>
I can't seem to find bin/dosemu.map is it created somewhere? I also 
don't know how to use gdb.
I was talking about the very old Duke Nukem (dn1.exe). The problem only 
seems to happen with simpler applications also ZSNES works fine for 
example. I'm using PC DOS 2000 (7.0 Rev 1) btw.
Julius

Re: ERROR: BUG: dosemu touched the protected video memory!!!

[Julius Schwartzenberg]

Bart Oldeman schreef:

>Were you talking about duke nukem 3d or some earlier duke?
>  
>
It still doesn't work with version 1.2.0 :(
You can download the Duke Nukem I was talking about here btw:
ftp://ftp.3drealms.com/share/1duke.zip
Julius

Re: ERROR: BUG: dosemu touched the protected video memory!!!

[Bart Oldeman]

On Sat, 24 Jan 2004, Julius Schwartzenberg wrote:

> Bart Oldeman schreef:
>
> >Were you talking about duke nukem 3d or some earlier duke?
> >
> >
> It still doesn't work with version 1.2.0 :(

yes, I know, noone has tried to fix it so far, and I didn't want to do it
myself because that would just delay 1.2.0 even more (ie. not classified
as "release critical"). Can you put it in the SF BTS (bugs link on
www.dosemu.org) so that it won't be forgotten easily?

Bart

Re: ERROR: BUG: dosemu touched the protected video memory!!!

[Bart Oldeman]

On Sat, 24 Jan 2004, Julius Schwartzenberg wrote:

> Bart Oldeman schreef:
>
> >Were you talking about duke nukem 3d or some earlier duke?
> >
> >
> It still doesn't work with version 1.2.0 :(
> You can download the Duke Nukem I was talking about here btw:
> ftp://ftp.3drealms.com/share/1duke.zip

yep, I downloaded that one. Seems to work fine for me though...
When would it happen?

I just did
xdosemu
cd duke
dn1
press "s" from main menu
press "space" twice
duke can walk left and right
which Linux kernel version are you running on? Distribution?

Can you also look up the value of eip in the dump and compare it to
bin/dosemu.map (you get this file when compiled from source code), and
give the full ~/.dosemu/boot.log contents?

Bart

(BTW Duke had a graphics glitch for me which was fixed in CVS but not in
-stable yet: but this as far as I can see should not be the cause for the
crash.
Fix:

--- src/env/video/vgaemu.c.~1.4.2.2.~	Sat Jan 17 21:59:10 2004
+++ src/env/video/vgaemu.c	Sun Jan 25 13:58:51 2004
@@ -2307,7 +2307,7 @@
  * Set visible text page.
  *
  * `vga.display_start' is set to `page' * `page_size'.
- * In graphics modes to 'page' * 'page_size' * 8 (quick workaround, FIXME!)
+ * In graphics modes the page_size is determined from memory/vga settings
  *
  * arguments:
  * page      - Number of the text page.
@@ -2320,7 +2320,13 @@
 int vga_emu_set_text_page(unsigned page, unsigned page_size)
 {
   if(vga.mode_class != TEXT) {
-    page_size *= 8;
+    page_size = vga.scan_len * vga.height;
+    if (page_size != 0) {
+      page_size = vga.mem.bank_pages * 4096 / page_size;
+      if (page_size != 0) {
+	page_size = vga.mem.bank_pages * 4096 / page_size;
+      }
+    }
   }

   if((page + 1) * page_size > vga.mem.size) {