Re: [PATCH #upstream] libata: implement libata.force module parameter

[Sam Ravnborg <sam@ravnborg.org>]

On Fri, Feb 01, 2008 at 12:28:35PM -0500, Jeff Garzik wrote:
> Tejun Heo wrote:
> >This patch implements libata.force module parameter which can
> >selectively override ATA port, link and device configurations
> >including cable type, SATA PHY SPD limit, transfer mode and NCQ.
> >
> >For example, you can say "use 1.5Gbps for all fan-out ports attached
> >to the second port but allow 3.0Gbps for the PMP device itself, oh,
> >the device attached to the third fan-out port chokes on NCQ and
> >shouldn't go over UDMA4" by the following.
> >
> > libata.force=2:1.5g,2.15:3.0g,2.03:noncq,udma4
> >
> >Signed-off-by: Tejun Heo <htejun@gmail.com>
> >---
> >I guess it's about time we add something like this.  More than
> >anything else this should help debugging and can serve as a last
> >resort to work around problems.
> >
> >Thanks.
> >
> > Documentation/kernel-parameters.txt |   35 +++
> > drivers/ata/libata-core.c           |  375 
> > +++++++++++++++++++++++++++++++++++-
> > drivers/ata/libata-eh.c             |    8 
> > drivers/ata/libata.h                |    1 
> > 4 files changed, 415 insertions(+), 4 deletions(-)
> 
> ACK, but it breaks the build due to section type conflicts:
> 
> drivers/ata/libata-core.c:108: error: ata_force_param_buf causes a 
> section type conflict
> 
> Given that the data is marked __initdata and the code is marked __init, 
> I cannot see the problem.

I have lost the actual patch.
But what you see is what happens when you mix const and non-const data
in the same section.

Look for use of __initdata for const data and replace it with __initconst.

And modpost cannot warn about it as gcc errors out before we look at the
.o file with modpost.

	Sam