Re: Kernel malloc/realloc?

From: Alex (AlX_at_a)
Date: 02/15/04 

Date: Sun, 15 Feb 2004 06:09:57 +0200

I'm getting really bored, really fast, Whatever, I know that...
And since you seem to support the look into RTL sources, learn kernel
programming, please share with the rest of the forum what you learn after
you look at those surces...

"David J. Craig" <SeniorDriversWriter@shogunyoshimuni.com.net> wrote in
message news:eXiWcT38DHA.2392@TK2MSFTNGP11.phx.gbl...
> No, stupid is calling functions belonging to Win32, 'SYSTEM'. Windows
> NT has a kernel that has several possible environments above it and one
> of them is Win32. There is or was a POSIX environment. They also had a
> OS/2 environment at one time because the OS/2 Brief would run under NT4.
> The use of the GlobalAlloc function is not even recommended since the
> overhead is high. So how does a function in kernel32.dll even belong in
> the 'Development Device Drivers' newsgroup? The first question was
> about allocating and reallocating memory under Windows 2000+.
>
> "Alex" <AlX@a> wrote in message
> news:Oi8rNa28DHA.488@TK2MSFTNGP12.phx.gbl...
> > Do you even know the diffrence between a RTL function and a System API
> > function?
> >
> > As it's been sed before, pointing to RTL source code to understand how
> > **SYSTEM** APIs work is stupid.
> >
> > Sorry, if it's ofensive, but this is what it is
> >
> > MSDN Library April 2003:
> > GlobalAlloc:
> > GMEM_MOVEABLE:
> > "Allocates movable memory. Memory blocks are never moved in physical
> memory,
> > but they can be moved within the default heap."
> >
> > **"never moved in physical memory"**
> >
> >
> > "Tim Roberts" <timr@probo.com> wrote in message
> > news:9c9r20dgm2d1drglccnmf30g73lj87r2u4@4ax.com...
> > > "Alex" <AlX@a> wrote:
> > > >
> > > >"Tim Roberts" <timr@probo.com> wrote:
> > > >
> > > >> "Alex" <AlX@a> wrote:
> > > >> >
> > > >> >"Tim Roberts" <timr@probo.com> wrote:
> > > >> >
> > > >> >Isn't the same allgorithm behing the user mode reallocation (not
> > > >necesarly
> > > >> >realloc, i'm shure this thread has nothing to do with the
> acctual
> > realloc
> > > >> >function :P) which we all use in user mode apps?
> > > >>
> > > >> No. Both relloc in the C run-time library and
> > LocalRealloc/GlobalRealloc
> > > >> use the new/copy/free model.
> > > >
> > > >Is that a fact? Or a beleif?
> > >
> > > The source code for Microsoft's C run-time library is included with
> Visual
> > > C++. You can look it up. If there's empty space following the
> block, it
> > > just expands the block. Otherwise, it's new/copy/free.
> > >
> > > Think about it for a bit. Your page table magic will ONLY work if
> all
> > heap
> > > allocations are done in units of whole pages. As soon as you have
> two
> > > objects in the same page, you can't alter the mapping without
> screwing up
> > > the other objects in the page. The C run-time malloc and the Win32
> heap
> > > alloc work in units of 32 bytes.
> > >
> > > >> in order to save page space. So, 80000000 has the DOS interrupt
> > vectors
> > > >> from physical address 0, 800C0000 has the VGA BIOS at physical
> address
> > > >> C0000, and so on.
> > > >
> > > >This mapping is documented behaviour? For what OS-es is it used?
> > >
> > > I've never seen it documented by Microsoft, but it's fact, and
> operating
> > > system routines rely on it. I know it's true for the NT-based
> systems
> > > (NT/2K/XP). It used to be true on Windows 3.1. I do not remember
> about
> > > 95/98.
> > > --
> > > - Tim Roberts, timr@probo.com
> > > Providenza & Boekelheide, Inc
> >
> >
>
>

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