Re: What is context?

[Peter Teoh <tteikhua@xxxxxxxxxx>]

Mulyadi Santosa wrote:

Hi ...

pardon me if I am not that good answering this kind of conceptual things.



On Fri, Mar 7, 2008 at 11:18 AM, Peter Teoh <htmldeveloper@xxxxxxxxx> wrote:
  

What is "context"?
    

simple, it's context. Be it kernel mode context - user mode context,
kernel space - user space context, interruptible - atomic context.

So, it depends on what do you talk about. IMHO, context itself refers
to "attributes and environment that describe the situation". For
example, in interruptible - atomic context, we focus on whether there
is a chance interrupt is coming (and whether interrupt is non
blocked), or whether we should make it non interruptible.

In other word...put it simple, to define "context", we need to know
"the context of the situation"
  

You are right on the last part.....and this is the part that confused me in the past.

Now I understand:

context can mean:   userspace vs kernelspace context, meaning it mapped to CPL 3 or CPL 0 (ring3 or ring0) in hardware terms.

context can mean also:   interrupt vs process context, again it mapped to Intel x86 2 different mode of processing -> interrupt vs non-interrupt mode, and this can happen at any ring level.

other than this 2, i don't think there is any other different interpretation to context - it is always one of these that is meant.

With the above understanding, it is much better knowing why things have to be certain ways - as I can always fall back on intel's manual......but not necessary always.   cannot remember ( :-( )which piece of document though (in Documentation directory).

Thanks :-).




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