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Re: [Qemu-devel] [PATCH] Better support for dma_addr_t variables
From: |
David Gibson |
Subject: |
Re: [Qemu-devel] [PATCH] Better support for dma_addr_t variables |
Date: |
Sat, 31 Mar 2012 19:49:16 +1100 |
User-agent: |
Mutt/1.5.21 (2010-09-15) |
On Fri, Mar 30, 2012 at 11:32:45AM +0200, Andreas Färber wrote:
> Am 27.03.2012 04:43, schrieb David Gibson:
> > A while back, we introduced the dma_addr_t type, which is supposed to
> > be used for bus visible memory addresses. At present, this is an
> > alias for target_phys_addr_t, but this will change when we eventually
> > add support for guest visible IOMMUs.
> >
> > There are some instances of target_phys_addr_t in the code now which
> > should really be dma_addr_t, but can't be trivially converted due to
> > missing features which this patch corrects.
> >
> > * We add DMA_ADDR_BITS analagous to TARGET_PHYS_ADDR_BITS. This is
> > important where we need to make a compile-time (#if) based on the
> > size of dma_addr_t.
> >
> > * We add a new helper macro to create device properties which take a
> > dma_addr_t, currently an alias to DEFINE_PROP_TADDR().
> >
> > Signed-off-by: David Gibson <address@hidden>
> > ---
> > dma.h | 1 +
> > hw/qdev-dma.h | 4 ++++
> > 2 files changed, 5 insertions(+), 0 deletions(-)
> > create mode 100644 hw/qdev-dma.h
> >
> > diff --git a/dma.h b/dma.h
> > index 05ac325..463095c 100644
> > --- a/dma.h
> > +++ b/dma.h
> > @@ -32,6 +32,7 @@ struct QEMUSGList {
> > #if defined(TARGET_PHYS_ADDR_BITS)
> > typedef target_phys_addr_t dma_addr_t;
> >
> > +#define DMA_ADDR_BITS TARGET_PHYS_ADDR_BITS
> > #define DMA_ADDR_FMT TARGET_FMT_plx
> >
> > struct ScatterGatherEntry {
> > diff --git a/hw/qdev-dma.h b/hw/qdev-dma.h
> > new file mode 100644
> > index 0000000..e407771
> > --- /dev/null
> > +++ b/hw/qdev-dma.h
> > @@ -0,0 +1,4 @@
> > +#include "qdev-addr.h"
> > +
> > +#define DEFINE_PROP_DMAADDR(_n, _s, _f, _d) \
> > + DEFINE_PROP_TADDR(_n, _s, _f, _d)
>
> Is a new header just for this really needed? It's not being used in this
> patch, so its necessity is hard to judge. ;)
>
> I would've expected DEFINE_PROP_... in qdev.h along the others.
Well, it's dependent on DEFINE_PROP_TADDR() which is in qdev-addr.h
and not in qdev.h, as well as on dma_addr_t which is in dma.h. It
will generally be replacing DEFINE_PROP_TADDR too, so making it a
separate header seemed the most straightforward approach.
If someone has a definitive decision that a different way is better, I
can update for that. But I really hope we can avoid bikeshedding on
this for a month before merging.
--
David Gibson | I'll have my music baroque, and my code
david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_
| _way_ _around_!
http://www.ozlabs.org/~dgibson