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From: Marin Mitov <mitov@issp.bas.bg>
To: linux-kernel@vger.kernel.org
Cc: netdev@vger.kernel.org
Subject: CONFIG_HIGHMEM or CONFIG_HIGHMEM64G in illegal_highdma()
Date: Wed, 7 May 2008 19:49:54 +0300	[thread overview]
Message-ID: <200805071949.54583.mitov@issp.bas.bg> (raw)

Hi all,

The usage of NETIF_F_HIGHDMA in drivers/net/* make me think its 
purpose is to declare drivers's capability to address RAM above 4GB, OK?

For x86_64 CONFIG_HIGHMEM is not defined, so the function 
illegal_highdma() found in net/core/dev.c returns 0 because 
x86_64 has IOMMU mapping all RAM.

For x86_32 CONFIG_HIGHMEM is defined as 
(CONFIG_HIGHMEM4G || CONFIG_HIGHMEM64G)
While CONFIG_HIGHMEM4G insures RAM is bellow 4GB some checks
are unnecessarily done. 

Should we have CONFIG_HIGHMEM64G in illegal_highdma()
instead of CONFIG_HIGHMEM? If so should I post a patch?

Regards.

Marin Mitov

P.S. This is a resend, due to recent problems with http://lkml.org/

             reply	other threads:[~2008-05-07 16:50 UTC|newest]

Thread overview: 2+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2008-05-07 16:49 Marin Mitov [this message]
  -- strict thread matches above, loose matches on Subject: below --
2008-05-06 12:35 Marin Mitov

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