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Date:      Tue, 21 Jan 2003 22:41:48 -0500
From:      Bosko Milekic <bmilekic@unixdaemons.com>
To:        Alfred Perlstein <bright@mu.org>
Cc:        arch@freebsd.org
Subject:   Re: M_ flags summary.
Message-ID:  <20030121224148.A75236@unixdaemons.com>
In-Reply-To: <20030122023246.GP42333@elvis.mu.org>; from bright@mu.org on Tue, Jan 21, 2003 at 06:32:46PM -0800
References:  <20030122023246.GP42333@elvis.mu.org>

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On Tue, Jan 21, 2003 at 06:32:46PM -0800, Alfred Perlstein wrote:
[...]
> Peter has made a suggestion that we ressurect the WAIT "flags" for
> KLD_MODULES.  I'm do not object to it, but I do not think it's
> needed.
> 
> Reasons for not bringing back or changing the flags:
>   1) we'll go back to having the same problems.
>   2) if we change the 0'd flag to 0x2 then we:
>        waste a bit and
>        have a failure case where the default was fine.
>   3) garbage in cvs.

  I think that defining M_TRYWAIT and M_WAITOK to 0 for KLD_MODULES is
  fine but I do not think that defining them to anything other than 0 is
  fine just so that we could add that KASSERT() that Warren suggested in
  the allocation code.  As you point out, defining it to anything other
  than 0 would actually break ABI compatibility.  Defining it to 0 for
  KLD_MODULES would preserve both API and ABI compatibility for those
  who actually care.  Certainly, both M_TRYWAIT and M_WAITOK would have
  to be defined in order to maintain full backwards-API compatibility.

  This would solve the compatibility issue, it would give us the default
  "wait" behavior that your change introduced, and it would be a very
  small delta to what has already been committed.

> Personally I would like to see M_NOWAIT defined in a single place
> rather than in both malloc.h and mbuf.h, anyone have a suggestion
> for that?

  Ditto.  I don't have a suggestion, though. :-(

> -- 
> -Alfred Perlstein [alfred@freebsd.org]
> 'Instead of asking why a piece of software is using "1970s technology,"
>  start asking why software is ignoring 30 years of accumulated wisdom.'

-- 
Bosko Milekic * bmilekic@unixdaemons.com * bmilekic@FreeBSD.org


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