Re: [Gumstix-users] how to increase kernel DMA size

[Jason G. <jgo...@gm...>]

Hi Dave,

I followed your instructions for rebuilding the kernel and put a printk in
the consistent_init function.  I can see that my changes were applied
correctly via the printk, but the call to dma_alloc_writecombine is still
returning 0.  Do you have any other ideas why this still doesn't work?  I
appreciate all of your help.

Thanks,
Jason

On Mon, Aug 25, 2008 at 10:45 AM, Dave Hylands <dhy...@gm...> wrote:

> Hi Jason,
>
> > I tried changing CONSISTENT_DMA_SIZE to SZ_16M and saw the same results.
> > Here is what I did to rebuild the kernel after I made the change to
> > memory.h:
> >
> > 1) In gumstix-buildroot/build_arm_nofpu/linux-2.6.21gum
> >
> > make ARCH=arm CROSS_COMPILE=../staging_dir/bin/arm-linux-uclibcgnueabi-
> >
> > 2) In gumstix-buildroot
> >
> > make
>
> What I normally do, is:
>
> cd gumstix-buildroot
> rm build_arm_nofpu/linux-2.6.21gum/arch/arm/boot/compressed/vmlinux
> make
>
> > When this completed and a new rootfs.arm_nofpu.jffs2 and uImage were
> created
> > I reflashed the gumstix with the new kernel.  Is this the correct
> procedure
> > to get the DMA size change on the gumstix?  If this looks correct, do you
> > know what else I could be doing wrong?
>
> I'd recommend adding a printk somewhere in the kernel that prints out
> the size. That way you'll have positive confirmation that you've
> modified things correctly.
>
> I'd probably put the printk in the arch/arm/mm/consistent.c file in
> the consistent_init function.
>
> --
> Dave Hylands
> Vancouver, BC, Canada
> http://www.DaveHylands.com/
>
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