Subject:
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Re: Modifying the BrickOS source code
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Newsgroups:
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lugnet.robotics.rcx.legos
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Date:
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Tue, 15 Jul 2003 22:55:07 GMT
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Viewed:
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2855 times
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Here is a visual representation:
[ KERNEL ]mm_start[ HEAP ]
The heap will contain ALL of the following: User Programs, User
Allocated memory, Kernel allocated memory (not including static/global
variables and constants).
The only thing that is prior to mm_start is the Kernel (code and variables)
You will discover that the memory manager and other parts of the code
will check pointers for "less than mm_start" as well as "greater than
mm_start". This is done for various reasons including:
... Is the calling code part of the kernel or a user program?
... Have I reached the end of memory (pointer will wrap to the beginning)
Hopefully this is more clear; it is a challenging piece to explain.
// Joe
Michael Martelli wrote:
> In lugnet.robotics.rcx.legos, Joseph Woolley wrote:
>
> > However, it is worth noting, mm_start is the end of the Kernel code. So
> > mm_start is also used to determine if a piece of code is part of the
> > kernel or a user program. User programs are located above mm_start
> > since the kernel will allocate memory for them when they are downloaded
> > (dll)
>
>
> Thanks for the description Joe, but in the above paragraph you seem to
> contradict yourself, you say that mm_start is the end of kernel mode, but alos
> that user programs are located above mm_start
>
> I do not understand that part, did you mean user programs are located below
> mm_start? or am I just not seeing the big picture here?
>
> Thanks,
> Mike
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Message has 1 Reply:
Message is in Reply To:
 | | Re: Modifying the BrickOS source code
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| (...) Thanks for the description Joe, but in the above paragraph you seem to contradict yourself, you say that mm_start is the end of kernel mode, but alos that user programs are located above mm_start I do not understand that part, did you mean (...) (21 years ago, 15-Jul-03, to lugnet.robotics.rcx.legos)
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