Re: [ros-dev] Re: [ros-svn] [hbirr] 15821: - Changed the calculation of the base address of an image section.

[Alex Ionescu]

Hartmut Birr wrote:

>  Alex Ionescu wrote:
>
>   
>
> >  If you're up for it, here are the public NT
> > structures used...maybe it
> > won't be a bad idea if we use them if it's not too much code change:
> >
> >
> > I think it's important because many of the Section implementation
> > details are documented in books (including driver-related books) and
> > known to driver developers who might be using the structures in their
> > code... I can name NT Insider, Windows Internals 4th Edition and
> > Windows NT File System Internals as some examples...but anyways it's
> > just an idea.
> >     
> >  
> I think that the structures are not public. 
>  
Where did I paste them from...?

>  No driver can use this
> structures. 
>  
You live in a dream world. I can get many drivers use this. I will keep 
referring to one example of horrible kernel code: the NVIDIA driver 
reads a static, hard-coded pointer inside kernel32 (from kernel-mode!). 
If a well known company does this, how much do you want to bet other 
drivers certaintly poke around in structures. It's a complete illusion 
to think that every driver doesn't. NT Insider recently talked about a 
WHQLed driver that instantly ASSERTS on a debug build; driver quality is 
truly horrible. We have the option to support more drivers by imitating 
public structures; it's in our best interest to do so.

>  M$ can change the structures between service packs. 
>  
Yes, and they can also rename "Windows" to "Alexows" and
declare Paged 
Pool memory deprecated. The fact is they won't. MS takes great care to 
ensure that structures they know drivers are "illegaly" using don't 
change to the point that they will break the drivers.

>  IMO it
> exsits no reason to use exactly the same structures. 
>  
Well I've just pointed them out. However, if it takes considerable 
effort to do so, then we can forget about it for now.

>  In the near future,
> I will do some changes. It is necessary to split the segment structure
> in one large 'page' table and some short structures for each segment. 
>  
At least that will match the general implementation details.

>  It
> is nearly the same like the control area, the subsections and the
> segment. 
>  
Yes..

>  It is also necessary to use only one memory area for a
> mapped
> image section. I need this to implement the executing of low alignment
> executables (like device drivers).
>   
>  
Oh...so this is why they don't work! I'm glad to find this out! :)

>    
>
> >  There's even a nice diagram in one of the
> > books:
> >
> >     
> >  
> I know this diagram because I own some of the books.
>   
>  
So therefore the implementation details are public and as I pointed out 
the structures too. What's to stop a driver from using them?

>    
>
> >  As a sidenote, do we have a PFN Database? 
> >     
> >  
> We have a 'PFN' database. It is in freelist.c.
>   
>  
Thanks...but I'll suppose it's nothing like the NT implementation :)

>  - Hartmut
>
>   
>  
Best regards,
Alex Ionescu

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