Re: [PATCH RFC 2/3] x86-64: Calgary IOMMU - Calgary specific bits

[Olof Johansson]

On Tue, Mar 14, 2006 at 06:55:15PM -0600, Jon Mason wrote:
> On Wed, Mar 15, 2006 at 12:03:06AM +0100, Pavel Machek wrote:
> > Hi!
> > 
> > > +union tce_entry {
> > > +   	u64 te_word;
> > > +	struct {
> > > +		unsigned int  read     :1;   /* read allowed */
> > > +		unsigned int  write    :1;   /* write allowed */
> > > +		unsigned int  hubid    :6;   /* hub id - unused */
> > > +		unsigned int  rsvd     :4;   /* reserved */
> > > +		unsigned long rpn      :36;  /* Real page number */
> > > +		unsigned int  unused   :16;  /* unused */
> > > +	} bits;
> > > +};
> > 
> > I'd say this is going to be pretty flakey.
> 
> Why do you think this would be flakey?  It's nearly identical to the
> tce_entry definition in include/asm-powerpc/tce.h (endien swapped, of
> course).

We're killing structures like that one by one on PPC, I just haven't
gotten around to dealing with tce_entry yet.

The way to do it is to use masking and shifting by hand.


-Olof
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