Re: [PATCH 2/2] drm/i915: use size_t instead of u32 for stolen memory size variables

[Joonas Lahtinen <joonas.lahtinen@linux.intel.com>]

On Tue, 2017-09-26 at 21:13 +0100, Chris Wilson wrote:
> Quoting Paulo Zanoni (2017-09-26 20:29:08)
> > Stolen memory pointers are dma_addr_t, which means they can be 64 bit
> > things. By using u32 we leave room for bugs in case we ever get huge
> > amounts of stolen memory. By using size_t we don't risk running into
> > those problems.
> > 
> > Cc: Chris Wilson <chris@chris-wilson.co.uk>
> > Signed-off-by: Paulo Zanoni <paulo.r.zanoni@intel.com>
> > ---
> >  drivers/char/agp/intel-gtt.c           | 10 +++++-----
> >  drivers/gpu/drm/i915/i915_gem_gtt.c    |  2 +-
> >  drivers/gpu/drm/i915/i915_gem_gtt.h    |  6 +++---
> >  drivers/gpu/drm/i915/i915_gem_stolen.c | 19 +++++++++----------
> >  include/drm/intel-gtt.h                |  2 +-
> >  5 files changed, 19 insertions(+), 20 deletions(-)
> > 
> > diff --git a/drivers/char/agp/intel-gtt.c b/drivers/char/agp/intel-gtt.c
> > index 9b6b602..a1db230 100644
> > --- a/drivers/char/agp/intel-gtt.c
> > +++ b/drivers/char/agp/intel-gtt.c
> > @@ -80,7 +80,7 @@ static struct _intel_private {
> >         unsigned int needs_dmar : 1;
> >         phys_addr_t gma_bus_addr;
> >         /*  Size of memory reserved for graphics by the BIOS */
> > -       unsigned int stolen_size;
> > +       size_t stolen_size;
> 
> What is size_t? How does that correspond to a physical or dma addr?
> You either meant kernel_size_t or unsigned long, or a proper type for
> the address space.

We're using phys_addr_t + size_t in early-quirks.c too, so we want to
keep both places consistent. If we're using something else than size_t,
then we should update both places (it's still on my todo to get rid of
the code duplication).

Regards, Joonas
-- 
Joonas Lahtinen
Open Source Technology Center
Intel Corporation
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