Subject: Re: how to deftopt, was The demise of DEV_BSIZE
To: Bill Studenmund <wrstuden@nas.nasa.gov>
From: Jason Thorpe <thorpej@nas.nasa.gov>
List: tech-kern
Date: 10/07/1999 14:07:46 
On Thu, 7 Oct 1999 13:04:55 -0700 (PDT) 
 Bill Studenmund <wrstuden@nas.nasa.gov> wrote:

 > #ifdef PO2_ONLY 	/* or whatever we name it - my names suck */
 > #define	btodb(x, sh)	((x) >> (sh))
 > etc.
 > #else
 > #define btodb(x, sh)	((sh >= 0) ? ((x) >> (sh)) : ((x) / (-sh))
 > etc.
 > #endif	/* PO2_ONLY */
 > 
 > That way the right thing just happens with one test. But
 > 
 > #if defined(NON_PO2) || defined(LKM) works too.
 > 
 > Thoughts?

Yes.  Your latter proposal.  With a twist.

#if defined(_KERNEL) && !defined(_LKM)
#include "opt_oddblocksize.h"
#endif

#if !defined(_KERNEL) ||						\
    (defined(_LKM) || defined(ODDBLOCKSIZE))
#define	btodb(x, sh)	((sh >= 0) ? ((x) >> (sh)) : ((x) / (-sh))
#else
#define	btodb(x, sh)	((x) >> (sh))
#endif

...that way userland get the premium version, too.

        -- Jason R. Thorpe <thorpej@nas.nasa.gov>