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Re: about roottask`s utcb ?


From: Espen Skoglund
Subject: Re: about roottask`s utcb ?
Date: Tue, 16 Sep 2003 16:02:15 +0200

[Yu Neil]
> I have a problem, Why the roottask`s utcb locate in 0xbf000100 ?

Since the roottasks are not created by the user, the user has no
control of where to locate the UTCB and KIP areas.  The kernel
therefore arbitrarily chooses a virtual address (which happens to be
0xbf000000 and upwards).

In a real system one will of course want to control the location of
these memory areas.  The idea is to have the bootloader (kickstarter)
put these locations in the kernel configuration page, but this is not
yet specified in the reference manual.

> and accessing address of 0xbf000100 will not cause pagefault , why ?

This is a virtual memory address.  The virtual memory at this location
is backed by the UTCB memory.  There's no magic going on here.

        eSk





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