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Groups > linux.debian.bugs.dist > #922972

Bug#911211: Increase default CMA size for armhf kernels

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On Wed, 2018-10-17 at 06:27 +0000, Priit Laes wrote:
> Package: linux-image-armmp-lpae
> Version: 4.18+98~bpo9+1
> 
> Debian Stretch
> 
> Currently, the default CMA size for armhf kernels is set to 16M.
> CMA allocator is used by display engine for storing framebuffer data.
> 
> At least on sunxi platform (specifically OLinuxino-Lime2-eMMC device)
> it causes issues with larger displays (namely 1920x1080), because Xorg
> fails to start with following cryptic message:
[...]

The need for CMA is highly dependent on the hardware and applications
used.  So I don't think we can set a default which will please
everyone.  You can always override the built-in default size using the
cma parameter on the kernel command line.

That said, it seems reasonable to raise the default - when it is larger
than needed, the pages not allocated to the drivers that need it can
still be allocated to user processes, just not for other in-kernel
purposes.

Ben.

-- 
Ben Hutchings
Man invented language to satisfy his deep need to complain.
                                                          - Lily Tomlin

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Bug#911211: Increase default CMA size for armhf kernels Priit Laes <plaes@plaes.org> - 2018-10-17 08:40 +0200
  Bug#911211: Increase default CMA size for armhf kernels Ben Hutchings <ben@decadent.org.uk> - 2018-10-17 13:20 +0200

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