[Intel-gfx] [RFC 0/2] Compile out integrated

Lucas De Marchi lucas.demarchi at intel.com
Tue Feb 1 17:28:20 UTC 2022

On Tue, Feb 01, 2022 at 07:09:14PM +0200, Jani Nikula wrote:
>On Tue, 01 Feb 2022, Lucas De Marchi <lucas.demarchi at intel.com> wrote:
>> On Tue, Feb 01, 2022 at 11:15:31AM +0000, Tvrtko Ursulin wrote:
>>>From: Tvrtko Ursulin <tvrtko.ursulin at intel.com>
>>>Quicky and dirty hack based on some old ideas. Thought maybe the approach might
>>>interest the Arm port guys. But with IS_GEN_RANGE removed easy gains are not so
>>>big so meh.. Maybe some more easy wins with IS_DISPLAY_VER but I haven't looked
>>>into that side.
>>> 3884664  449681    6720 4341065  423d49 i915.ko.tip
>>> 3599989  429034    6688 4035711  3d947f i915.ko.noigp
>> By these numbers probably it's hard to justify. Another thing to consider
>> is that it's very common to have on the same system both
>> integrated and discrete - doing this would remove at compile time any
>> chance of driving the integrated one.
>I guess the point was, the arm systems won't have integrated, and it's
>anyway going to be a separate build.

so probably the focus and argument here should not be about size
reduction. From patch 1 I see:

+       bool "Support integrated GPUs"
+       default y
+       depends on DRM_I915
+       help
+         Include support for integrated GPUs.

If it's something that depends on arch rather than providing an
option in menuconfig, then I think it could be some interesting
investigation. However, I can't see how it would help with removing
some code paths in the driver (e.g. the clflush() calls we were talking
about in another patch series) since the code elimination would all
happen at link time.

Lucas De Marchi

>> Lucas De Marchi
>>>Note debug kconfig so everything is inflated. Whether or not the relative gain
>>>would change with production kconfig I am not sure.
>>>I was a bit curious there were no build errors around functions no longer used
>>>so either there were none (would mean patch is not really that effective), or
>>>something changed with compiler warnings/smarts. Haven't looked into it.
>>>Tvrtko Ursulin (2):
>>>  igp kconfig
>>>  jsl/ehl
>>> drivers/gpu/drm/i915/Kconfig                  |   5 +
>>> drivers/gpu/drm/i915/Kconfig.platforms        |   7 +
>>> .../drm/i915/display/intel_ddi_buf_trans.c    |   4 +-
>>> drivers/gpu/drm/i915/display/intel_dpll_mgr.c |   2 +-
>>> drivers/gpu/drm/i915/i915_drv.h               | 128 +++++++++++-------
>>> drivers/gpu/drm/i915/i915_pci.c               |  44 +++++-
>>> 6 files changed, 134 insertions(+), 56 deletions(-)
>>> create mode 100644 drivers/gpu/drm/i915/Kconfig.platforms
>Jani Nikula, Intel Open Source Graphics Center

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