CONFIG_HIGHMEM or CONFIG_HIGHMEM64G in illegal_highdma()

From: Marin Mitov
Date: Wed May 07 2008 - 12:50:28 EST


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/
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/