memory reported to OS

Eric W. Biederman ebiederman at lnxi.com
Thu Jan 20 08:36:01 CET 2005


"Gin" <ginlin at nexcom.com.tw> writes:

> Is it mandatory to report Reserved Memory region to the OS? For example,
> the IOAPICs memory-mapped addresses? 

Reserving the address of any IO devices is a BUG BUG BUG.
Your kernel will not boot if it doing things properly.

> Would that be a problem if Linux
> kernel didn't see it be claimed as RESERVED? 

More likely the reverse.
  
> It seems Linuxbios doesn't claim any memory regions as RESERVED.

We reserve out tables.

Reserving memory is to tell the OS to never ever touch it (at least that
is the linux interpretation).  So if there is some magic hardware that
the OS never sees we may want to reserve that.  But mostly it is about
reserving memory that is used for another purpose.  And we just
have a couple of tables which are pretty small.

We really should communicate the address of non probable devices but
that work is in process.

Eric



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