On Thu, 2 Jan 2020 at 11:44, Chris Wilson <chris@xxxxxxxxxxxxxxxxxx> wrote:
>
> Quoting Matthew Auld (2020-01-02 11:39:41)
> > On Thu, 2 Jan 2020 at 10:38, Chris Wilson <chris@xxxxxxxxxxxxxxxxxx> wrote:
> > >
> > > Create a vmap for discontinguous lmem objects to support
> > > i915_gem_object_pin_map().
> >
> > Yes, please.
> >
> > >
> > > Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
> > > Cc: Matthew Auld <matthew.auld@xxxxxxxxx>
> > > ---
> >
> > [snip]
> >
> > > @@ -288,12 +284,28 @@ static void *i915_gem_object_map(struct drm_i915_gem_object *obj,
> > > pgprot = pgprot_writecombine(PAGE_KERNEL_IO);
> > > break;
> > > }
> > > - addr = vmap(pages, n_pages, 0, pgprot);
> > >
> > > - if (pages != stack_pages)
> > > - kvfree(pages);
> > > + if (i915_gem_object_has_struct_page(obj)) {
> > > + struct sgt_iter iter;
> > > + struct page *page;
> > > + pte_t **ptes = mem;
> > > +
> > > + for_each_sgt_page(page, iter, sgt)
> > > + **ptes++ = mk_pte(page, pgprot);
> > > + } else {
> > > + const resource_size_t iomap = obj->mm.region->iomap.base;
> > > + struct sgt_iter iter;
> > > + dma_addr_t addr;
> > > + pte_t **ptes = mem;
> > > +
> > > + for_each_sgt_daddr(addr, iter, sgt)
> >
> > addr -= region.start; for poor old fake local-memory.
>
> Positive? I wasn't sure since we are using the physical address and not
> a mapping within the mapping?
I think so. It's 1:1 mapped so:
fake_lmem_start = 4G;
iomap = mappable_aperture_start;
daddr = fake_lmem_start + n;
n = daddr - fake_lmem_start;
io_addr = iomap + n;
>
> It's hard to tell, since so long as the address exists we can read/write
> to it, and only later pay the consequences of corrupting someone else's
> memory.
BAT results should tell us, where we write from the gpu and then read
from the cpu.
> -Chris
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