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Number : 522 Date : 2001-08-04 Author : Michael Marquart Subject : Re: lite version?? Size(KB) : 6
Hi Kan. I Upx'ed my win98se\system directory and it shrunk from 137 Meg to 75 Meg, although some files were skipped for various reasons. I wlll not attempt to use the UPX'ed versions as I consider toying with basic operating system files to be a shortcut to instability. Anyway, with modern multi gigabyte HDD it doesn't make much sense to skimp for a 100 megabytes here or there. Thanks for your discussion of the PE format file operation - I am a little wiser than before. Michael On Sat, 04 Aug 2001 09:25:36 -0500, Kan Yabumoto wrote: > >Michael, > >Thank you for the pointer to UPX which is quite intriguing. > >I went there and read the material in the web page. It >is very intersting. > >It is ideal when the XXCOPY16 program need to be moved over >to a tight space medium such as the floppy. On the other >hand, it incurs a performance penalty on every execution. >What should be noted is that the Win32 PE file format (the >32-bit common execution program file format) was designed >with an efficient virtual memory implementation in mind. >That is, the executable program file itself acts as the >swap file for the program while it is running. That is, >when XXCOPY.EXE is being run, only the necessary chunks of >the XXCOPY file are brought into the main memory (by the >4KB granularity) on an as-needed basis (using the demand- >paging scheme). In a typical XXCOPY execution, the help >text (either the alphabetic version /HELPA or the unsorted >version /HELP) which occupies a substantial amount of memory >(about 50 KB altogether) is never accessed and therefore >will remain on the program file (disk) without ever even >brought into the main memory. In a way, knowing this, we, >the programmer can be somewhat lazy in adding extra code which >is seldom executed and therefore, even though the overall >program size would increase, it would not add any performance >penalty being just a very large executable program. > >I'm afraid that these hidden benefits of the PE file format >will be all lost when we compress the program into a >self-extracting file on the fly. Moreover, the expanded >program will probably remain in the virtual memory space >which reduces the amount of available virtual memory space >by that much. That is, I assume the UPX stub portion will >probably uncompress the entire program file rather than >to uncompress small portion at a time on demand and does not >even try the portion which is not being utilized for a >particular run. In other words, the superficial benefit of >having a small file size will add substantial burden on the >system resource in the Win32 environment. If that is the >case, there is little advantage using the technique for >the 32-bit version. > >On the other hand, for XXCOPY16, it has a totally different >outlook. First of all, as a DOS program, the uncompressed >file image will very likely remain in the regular memory >area (the 640 KB regular DOS memory space) and little impact >on the virtual memory related issues discussed above. And, >this is where the original motivation for reducing the >program size. So, if we were to seriously consider the use >of the UPX technique, it will be limited to the XXCOPY16.EXE >program. > > ------------------------------------------------------------ > Currently, there is a minor inconvenience if we apply > this technique now. That is, the current method of the > built-in version-detector mechanism implemented by XXCOPY > will stop working unless it is replaced by a different > scheme --- when you install a new version of XXCOPY, it > will scan the target directory for an older version of > XXCOPY.EXE and XXCOPY16.EXE and locate a signature value > in the file to determine the version number of earlier > release. This allows XXCOPY to rename the older version > using the version number. > ----------------------------------------------------------- > >The easiest way for us is to show the technique for those >who want to use the compression, in order to squeeze the >program into the floppy, and let the willing parties to do >their own work. The proper way is for us to remove >fat and come up with the "lite" version (which you could >further shrink using the UPX technique). > >To answer to Michael's question, yes, it is worth giving >some thought on a limited basis on the XXCOPY16.EXE version. > >Incidentally, I was trying to see how efficient their >compression algorithm was. By PKZIPping the XXCOPY.EXE >(freeware v.2.60.0), the 262,144-byte file becomes >106,273 bytes. According to Michael, the UPXed file is > 99,328 bytes (with the self-extracting stub portion). >That is about 7% smaller than the ZIP stuff. That is >quite impressive. > >I wonder if Michael is interested in converting all of >the Windows .DLL and .EXE (found inside the >C:\windows\System directory) --- or better yet, in >Win2000's c:\winnt\system32 directory which is huge and >apply the UPX technique in every file you find there. >In theory, the entire windows directory size will become >less than half. The question is, what is the overall >impact to the system performance (especially to the >virtual memory usage)? If my reasoning (explained above >for the Win32 environment) is correct, the system >would probably die due to the virtual memory exhaustion >--- or just excessive thrashing). Anyway, this is my >guess. And, it is worth investigating. Any volunteers? > >Kan Yabumoto > >=========================================================== >At 2001-08-04 07:46, you wrote: > >>On this topic of compression, the UPX executable compressor reduced XXcopy >>from 262,144 to 99,328 bytes - and it's still executable. >> >>It will work on most MSdos exe,com,sys as well as windows executables. >>You may be able to create enough room on your boot floppy for the full XXcopy. >> >>Look here: >> >> The Ultimate Packer for eXecutables >> Copyright (c) 1996-2001 Markus Oberhumer & Laszlo Molnar >> http://wildsau.idv.uni-linz.ac.at/mfx/upx.html >> http://upx.sourceforge.net >> >> >>Kan, would you consider using for all xxcopy distributions? >> >>Michael >> >> >>On Fri, 03 Aug 2001 16:41:55 -0400, rotaiv wrote: >> >> >At 08/03/2001 02:11 PM, F. Schmultzburger wrote: >> > >> >>I have a fairly complete boot floppy that my collegues and I to use >> >>when dealing with clients computers when windows is screwed up. I >> >>really like XXCOPY, but it's much bigger than MS's XCOPY, and the boot >> >>disk has less than 10k to spare. >> > >> >Have you considered creating a CAB file and extracting the contents to a >> >RAM disk like the Win98 startup disk? I just compressed xxcopy 2.70.2 into >> >a CAB format and it is only 87KB (60% smaller). > > > > > >Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/ > >
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