[maemo-developers] [maemo-developers] DosBox

From: Eero Tamminen eero.tamminen at movial.fi
Date: Fri Aug 11 13:19:42 EEST 2006

Today I quickly tested whether DosBox 0.65 would work on the target.

Good news:
- Builds without problems
- 286/386 CGA/EGA/VGA games (not requiring FPU) would seem to work
  at "reasonable" speed
Bad news:
- Rest of the system does not work at all:
  1. Sometimes I cannot switch to Desktop at all
  2. After switching to Desktop, it can take 10
     mins until it has drawn itself
  3. Device reboots very easily

I don't know why 1) happens, the "Device mode" dialog comes up
without any problems.

I think the Desktop slowness and reboots are because DosBox takes
too much memory.  When looking (on x86) with "pmap" what DosBox
reserves, this catched my eye:
 25636K rwx--    [ anon ]

As it's writable, all of that 25MB is private to DosBox, which
is way too much for N770. I'm not sure how or why it's also
executable, the dynamic core was not enabled (which could have
created executable code into malloced memory).

If there were some way to significantly reduce this memory
allocation, or at least not dirty it by writing/zeroing more
of it than is necessary (I set DosBox to emulated 2MB of RAM),
DosBox could would work acceptably in N770.  According to Massif,
about 16MB of ram is malloced in DosBox MEM_Init().

	- Eero

PS. I tested also latest Rocks'n Diamonds and Toppler (Nebulus clone
from toppler.sf.net) games. Former took so much memory that the device
rebooted, but Toppler works just fine!

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