[igt-dev] [PATCH i-g-t] i915: Handle the case where legacy mmap is not available

[Dixit, Ashutosh]

On Tue, 11 May 2021 02:00:00 -0700, Maarten Lankhorst wrote:
>
> We will remove support for the legacy mmap ioctl, so handle that
> case without rewriting all tests.
>
> When the gem_mmap ioctl is not available, transparently fallback to
> mmap_offset.

Unless we've done something in the kernel, with this we should expect to
see failures when object size approaches available system memory since as
we know the mmap_offset page fault handler tries to pin the entire object
which would fail for large objects. The old gem_mmap doesn't have this
limitation.

With pread/pwrite gone, the only option for large objects was to gem_mmap
and read/write but appears that will now go away too.

See e.g.
https://patchwork.freedesktop.org/patch/426749/?series=88561&rev=3