Re: [ros-dev] Arwinss

[Timo Kreuzer]

Hi,

Some people might have already noticed that I have a "strong opinion"
regarding this rewrite. So let me explain my point of view here.

Aleksey, thanks for clarification and confirming a lot of what I already
thought. I hope you don't feel offended (at least not more than I was,
when browsing through your recent commits ;-))

I totally agree that we have a very limited number of devs and it takes
quite some time to get the stuff in the win32 subsystem done.
Anyway the "lets just use wine" shortcut won't work.

Any developer who has ever done any serious work on our win32 subsystem
might actually feel offended by this rewrite. It basically says: "Hey,
all your stupid attempts to remove the hacks and to make the win32
subsytem work more like Windows and less like crap, were totally a waste
of time. You should have instead better written a bunch more hacks
around the hacks to make all the wine code work".

Well, that's what we did long time ago, when the goal was "Get stuff
done now, fix bugs later" and that's what got us all the problems in the
first place. But we are past this stage since quite some time now. "No
more hacks!" that's the current deal. We have invested a great amount of
time into testing native api, using the Windows structures, fixing the
gdi handle manager, etc. What for? Doing it like windows does, means
100% chance that the approach will work, if properly implemented, it
allows better testing and analyzation and it helps to keep developers
from doing bs. Doing it like wine or inventing "new standards" will with
a chance of 50% result in great fail, as can be seen over and over again
in win32k.

Wine emulates the kernel through a server. Of cause we don't use it,
because it has a totally different design. We have an NT kernel and
every kernel developer would eat me alive if I tried to put a single
line of wine code into our kernel. It's considered crap there.
Well, Wine also emulates the win32 subsystem though a server. Again the
design isn't anywhere near the real win32 design. And yet you want to
use it? Be prepared to get eaten alive by a win32 developer when you try
to get anything like that into trunk. (I consider it as crap there!)

Fixing issues?
The idea that this rewrite could instantly fix all the issues, because
it works on wine, is a fancy idea. But it won't work. Wine is designed
to work on linux/X11 not on NT and that will come back at you sooner or
later. Also the fact that it was tested with thousands of apps doesn't
mean it works correctly. How do you expect stuff like mode switching to
magically start working when there's no wine code that calls a display
driver to do the job? How do you expect display drivers to work at all?
More hacks on top of the huge pile of hacks? And how do you deal with
missing functionality in wine code? Shove more code in there? Or ignore
it, like if wine doesn't need it, we also don't need it? Or again fork
the code?

Optimization later?
You cannot simply "optimize later". It never works that way. A decent
design is a precondition to optimization. Wine code, which is in this
case designed as a workaround (hack) can never be optimized.

Conclusion:
This rewrite does IMO not have any merit. It will at most create an
ugly, slow something with a ridiculous design.

If it's only some kind of sick joke somewhere between "The price is
right" and the developers edition of "How low can you go", and you
committed it only to share your fun, then.. well, go ahead, make me
laugh, too.

If you actually considered merging it, ... Only over my dead body!
If you want to use more wine code, install linux and wine. You can even
put a new logo on it and sell that if you want money. But keep it out of
our core components.

Also, instead of complaining about old bugs in the win32 subsystem, you
should better take a look at the kernel. Man, there's more than enough
work todo. What about cc? What about fastfat? What about 3rd party
filesystems? What about implementing MmSecureVirtualMemory? What about
usb?  What about smp? No, I'm not suggesting to use a linux kernel,
because it works stable since ages and has all the stuff we don't have...

Finishing with a recursive acronym "Wine is not enough!"

Regards,
Timo


Aleksey Bragin wrote:
>   Hello,
>  I've heard many question about a branch I was working on recently,  
>  arwinss, so I'd like to write some explanation (you may skip the  
>  boring history part of the message)
>
>  Arwinss is a rewrite (the most advanced so far out of all previous  
>  attempts) of some parts of the Win32 subsystem, namely the USER32 and  
>  GDI32 API interfaces, along with the kernel counterpart win32k.sys.  
>  The kernel32.dll, csrss, and other parts remain in their present  
>  condition, and getting bugfixes if they come in the way of a rewrite.
>
>  [History and reasoning part starts here]
>  Why rewrite and not fix an existing Win32 subsystem? Timo, James and  
>  all our other great developers were and are doing a great work. I put  
>  a considerable amount of time in it to fix problems too. But, since  
>  our project is a volunteer-driven one, everyone has a real life, real  
>  work to do, and is not able to sit 24 hrs researching Windows  
>  internal structures, inventing new algorithms, trying out thousands  
>  of applications, not to say about graphics drivers.
>  Time is ticking, Win32 is improving, but most annoying bugs are there  
>  for years - e.g. vmware installer hang, Firefox move the mouse bug,  
>  drawing glitches, concurrency hacks in the code ("if (!a) /* someone  
>  else was faster than us and already freed it */"), probable heap  
>  misusage (relying on our heap implementation for desktop heaps) and  
>  heap memory corruptions (I kept trying to update rtl/heaps to the  
>  newest Wine code - and always failed without any obvious reason),  
>  inability to change video mode on the fly, and the list can go on.
>
>  So I thought, that something should be done with it. I would even  
>  want to trade off some speed gain in favor of stability (optimizing  
>  is an enjoyable task which could be done later).
>
>  After teaming up with Stefan, we created an nwin32 branch - a totally  
>  stubbed out win23k, user32 and gdi32. They had exactly matched  
>  exports, and win32k had exactly same system calls and Windows 2003  
>  SP1's win32k.sys.
>  However, due to really huge amount of work, the branch didn't went  
>  farther than trying to boot Windows 2003 with it and see a few  
>  stubbed functions being called.
>
>  Since then I started thinking on an alternative design of a Win32  
>  subsystem. The idea turned out to be very simple, and is based on the  
>  following questions:
>  - Why put so much effort into keeping the internal win32k system  
>  calls interface the same as in Windows, why put so much effort in  
>  converting to internal Windows structures, if we don't have something  
>  working first?
>  - Why base on a stoneage Wine's code which James and Christoph  
>  occasionally sync, and all my attempts to get more people into this  
>  boring task failed?
>  - Why not use achievements of our closest project - Wine?
>
>  [End of reasoning, fancy stuff starts]
>
>  The result came by itself: Try to build up a win32 subsystem based as  
>  much on Wine code as possible, and using Wine's modular design.  
>  Before publicly announcing it, I have spent a month actually trying  
>  all that stuff, and surprisingly it went very well, and a nice  
>  byproduct: support of remote sessions via X Windows.
>
>  Proof of concept screenshots are here:
>  http://www.reactos.org/media/screenshots/2009/arw_xlog1.jpg
>  http://www.reactos.org/media/screenshots/2009/arw_xlog1.jpg
>
>  Noone has ever done this before: This is Windows 2003 inside VMware,  
>  running my custom Win32 subsystem, with an X graphics driver module,  
>  communicating with an X Server running in the host OS (Windows XP,  
>  XMing X windows server), and with ReactOS's winlogon.exe and  
>  msgina.dll (for ease of debugging and source code availability)!
>
>  Let's go straight to the architecture:
>
>  GDI32.dll and USER32.dll are ported Wine usermode code, with very few  
>  modifications. GDI32 and USER32 depend on two things: Gdi and User  
>  driver, and a server.
>
>  Gdi and User driver is a loadable DLL, which provides an abstraction  
>  of a graphics driver in the system through a certain set of APIs. A  
>  typical example of such a driver is winex11.drv, which routes all  
>  drawing to the X Windows "client". However, this is not very useful  
>  for a local system which has a Windows NT architecture, where there  
>  is no need for remote windows displaying.
>
>  The server. GDI32 and USER32 rely on the server for managing all  
>  global information. In Wine, the server is run as a usermode  
>  wineserver.exe process, which communicates with gdi32/user32 via  
>  custom RPC, and emulates quite a lof of stuff which Windows NT kernel  
>  provides by default. My decision was to convert the RPC protocol from  
>  a slow interprocess filedescriptors-based unix-specific invocations  
>  to a fast system calls to win32k module. This way, win32k contains  
>  small part (~300 kb vs 1.5Mb+) of wineserver's source code, which  
>  deals with windows, window classes, atoms, windows stations, desktops  
>  and other totally platform/implementation independent stuff. It will  
>  be reduced further, because I even ported their own object manager  
>  for win32 objects, which will be exchange to our native ntoskrnl's  
>  object manager soon, when the testing phase is over.
>
>  The graphics driver, kernelmode part. As I said above, it's not very  
>  convinient to fully rely on X Windows for graphics output, because  
>  it's just not possible to run it in an NT-based OS which has no Win32  
>  subsystem. Thus, I decided to create a totally native gdi/user driver  
>  ("winent.drv"), which would rely on win32k module to actually perform  
>  all drawing. However, compared to our current implementation, the  
>  drawing would be way more simple. For example, if currently LineTo  
>  operation in win32k involves complex PATHOBJ, maintaining graphics  
>  cursor -- all of that in a strictly windows compatible way because  
>  apps depend on it, in this alternative win32k, LineTo is a simple  
>  line drawing function: RosGdiLineTo(pDc, x1, y1, x2, y2). Same  
>  applies to other functions, including e.g. text output, where all  
>  rendering happens using a usermode freetype.dll, and win32k just  
>  needs to display bitmap glyphs got from gdi32.
>
>  Don't be scared if you don't understand all that right away. I will  
>  put up a good short summary, along with a TODO and FIXME lists, and a  
>  HACKING guide.
>
>  Just a few cool facts about the new win32 subsystem:
>  - Based on a solid, very well maintained codebase, used by commercial  
>  vendors.
>  - Ease of updating from upstream (vendor importing)
>  - Tested against more than 12 000 Windows applications (http:// 
>  appdb.winehq.org)
>  - ...
>
>  I think it's enough for the first introduction.
>
>
>  WBR,
>  Aleksey Bragin.
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