lib/ioctl_wrappers: Keep IGT working without pread/pwrite ioctls

The general direction at this time is to phase out pread/write ioctls
and not support them in future products. This means IGT must handle
the absence of these ioctls. This patch does this by modifying
gem_read() and gem_write() to do the read/write using the pread/pwrite
ioctls first but when these ioctls are unavailable fall back to doing
the read/write using a combination of mmap and memcpy.

Callers who must absolutely use the pread/pwrite ioctls (such as tests
which test these ioctls or must otherwise only use the pread/pwrite
ioctls) must use gem_require_pread_pwrite() to skip when these ioctls
are not available.

v1: Removed __gem_pread, gem_pread, __gem_pwrite and gem_pwrite
    introduced previously since they are not necessary,
    gem_require_pread_pwrite is sufficient
v2: Fix CI failures in gem_advise and gen9_exec_parse by introducing
    gem_require_pread_pwrite
v3: Skip mmap for 0 length read/write's
v4: Remove redundant igt_assert's
v5: Re-run
v6: s/EOPNOTSUPP/-EOPNOTSUPP/
v7: Rebase on latest master, skip gem_exec_parallel@userptr with
    gem_require_pread_pwrite
v8: Re-run
v9: Rebase

Acked-by: Dave Airlie <airlied@redhat.com>
Acked-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Reviewed-by: Zbigniew Kempczyński <zbigniew.kempczynski@intel.com>
Signed-off-by: Ashutosh Dixit <ashutosh.dixit@intel.com>

1 files changed, 1 insertions, 0 deletions

diff --git a/tests/i915/gem_tiled_pread_pwrite.c b/tests/i915/gem_tiled_pread_pwrite.c
index b73fa126..ef1e1b3c 100644
--- a/tests/i915/gem_tiled_pread_pwrite.c
+++ b/tests/i915/gem_tiled_pread_pwrite.c
@@ -114,6 +114,7 @@ igt_simple_main
 	
 	fd = drm_open_driver(DRIVER_INTEL);
 	igt_require(gem_available_fences(fd) > 0);
+	gem_require_pread_pwrite(fd);
 
 	count = gem_available_fences(fd) + 1;
 	intel_require_memory(2 * count, sizeof(linear), CHECK_RAM);