From: Will Jhun <wjhun@cisco.com>
To: Gilad Benjamini <yaelgilad@myrealbox.com>
Cc: linux-mips@linux-mips.org
Subject: Re: lwl-lwr
Date: Tue, 20 May 2003 11:34:36 -0700 [thread overview]
Message-ID: <20030520183436.GJ726@cisco.com> (raw)
In-Reply-To: <1053455551.996c4860yaelgilad@myrealbox.com>
Some free or "MIPS-like" CPUs don't implement it because of a patent
problem. I've seen at least one implementation on opencores.org that has
this (missing) feature.
Probably if the compiler were to emit lwl and lwr code via
__attribute__((packed)), these instructions would have to be emulated by
the kernel on such a CPU. I imagine this would be quite a bit worse than
just doing two normal loads and extracting the desired word.
Will
On Tue, May 20, 2003 at 06:32:31PM +0000, Gilad Benjamini wrote:
> Hi,
> About two months ago there was a discussion
> here about disabling lwl-lwr.
>
> Can someone shed some light on why the discussion
> emerged ?
>
> Is this a performance issue, a processor which
> doesn't support it, or something else ?
>
> If this is a performance issue, I'll be happy
> to hear more details.
>
> TIA
>
>
>
next prev parent reply other threads:[~2003-05-20 18:51 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2003-05-20 18:32 lwl-lwr Gilad Benjamini
2003-05-20 18:34 ` Will Jhun [this message]
2003-05-20 19:07 ` lwl-lwr Kevin D. Kissell
2003-05-20 19:07 ` lwl-lwr Kevin D. Kissell
2003-05-21 0:34 ` lwl-lwr Ralf Baechle
2003-05-21 9:56 ` lwl-lwr Maciej W. Rozycki
2003-05-21 13:40 ` lwl-lwr Kevin D. Kissell
2003-05-21 13:40 ` lwl-lwr Kevin D. Kissell
2003-05-21 12:49 ` lwl-lwr Alan Cox
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