[Intel-gfx] [PATCH] [v5] drm/i915/bdw: Only use 2g GGTT for 32b platforms

[Yang, Guang A]

Tested-by: "Yang, Guang A" <guang.a.yang at intel.com>
With this patch, the 32 bit system can be able to boot normally.



Best Regards~~

Open Source Technology Center (OTC)
Terence Yang（杨光）
Tel: 86-021-61167360
iNet: 8821-7360

> -----Original Message-----
> From: Intel-gfx [mailto:intel-gfx-bounces at lists.freedesktop.org] On Behalf Of
> Ben Widawsky
> Sent: Wednesday, May 28, 2014 7:53 AM
> To: Intel GFX
> Cc: Ben Widawsky; stable at vger.kernel.org; Widawsky, Benjamin
> Subject: [Intel-gfx] [PATCH] [v5] drm/i915/bdw: Only use 2g GGTT for 32b
> platforms
> 
> Daniel requested in the bug that I use a 3GB fallback size. Since this is not in
> the spec as a valid size, I decided against it. We could potentially add a patch to
> bump it to 3GB on top of this one.
> 
> This probably should be CC: stable - but I'll let the powers that be decide that
> one.
> 
> Regression from a revert of the revert:
> commit 7907f45bf9f67a1c5e5d4ae05bab428d7c2f43b2
> Author: Ben Widawsky <benjamin.widawsky at intel.com>
> Date:   Wed Feb 19 22:05:46 2014 -0800
> 
>     Revert "drm/i915/bdw: Limit GTT to 2GB"
> 
> v2: Change ifdef to 32b, instead of ifndef update comment
> 
> v3. Update comment to not wrap (Daniel).
> Update commit message
> 
> v4: s/CONFIG_32/CONFIG_X86_32 (Jani).
> 
> v5: s/CONFIG_x86_32BIT/CONFIG_x86_32, as meant in v4 s/32B/32b (chris)
> 
> Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=76619
> Cc: stable at vger.kernel.org
> Reviewed-by: Daniel Vetter <daniel.vetter at ffwll.ch>
> Signed-off-by: Rodrigo Vivi <rodrigo.vivi at gmail.com>
> Signed-off-by: Ben Widawsky <ben at bwidawsk.net>
> ---
>  drivers/gpu/drm/i915/i915_gem_gtt.c | 7 +++++++
>  1 file changed, 7 insertions(+)
> 
> diff --git a/drivers/gpu/drm/i915/i915_gem_gtt.c
> b/drivers/gpu/drm/i915/i915_gem_gtt.c
> index 931b906..eec820a 100644
> --- a/drivers/gpu/drm/i915/i915_gem_gtt.c
> +++ b/drivers/gpu/drm/i915/i915_gem_gtt.c
> @@ -1775,6 +1775,13 @@ static inline unsigned int
> gen8_get_total_gtt_size(u16 bdw_gmch_ctl)
>  	bdw_gmch_ctl &= BDW_GMCH_GGMS_MASK;
>  	if (bdw_gmch_ctl)
>  		bdw_gmch_ctl = 1 << bdw_gmch_ctl;
> +
> +#ifdef CONFIG_X86_32
> +	/* Limit 32b platforms to a 2GB GGTT: 4 << 20 / pte size * PAGE_SIZE */
> +	if (bdw_gmch_ctl > 4)
> +		bdw_gmch_ctl = 4;
> +#endif
> +
>  	return bdw_gmch_ctl << 20;
>  }
> 
> --
> 1.9.3
> 
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