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Bug#1138060: riscv64: please enable contiguous memory allocator (CMA) support, needed for HDMI displays

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  Bug#1138060: riscv64: please enable contiguous memory allocator (CMA) support, needed for HDMI displays Dominique Belhachemi <domibel@debian.org> - 2026-05-27 19:40 +0200
    Bug#1138060: riscv64: please enable contiguous memory allocator (CMA) support, needed for HDMI displays Aurelien Jarno <aurel32@debian.org> - 2026-05-27 22:00 +0200
      Bug#1138060: riscv64: please enable contiguous memory allocator (CMA) support, needed for HDMI displays Dominique Belhachemi <domibel@debian.org> - 2026-05-28 06:50 +0200
        Bug#1138060: riscv64: please enable contiguous memory allocator (CMA) support, needed for HDMI displays Aurelien Jarno <aurel32@debian.org> - 2026-05-28 23:50 +0200
    Bug#1138060: marked as done (riscv64: please enable contiguous  memory allocator (CMA) support, needed for HDMI displays) "Debian Bug Tracking System" <owner@bugs.debian.org> - 2026-05-29 06:40 +0200

#92792 — Bug#1138060: riscv64: please enable contiguous memory allocator (CMA) support, needed for HDMI displays

Source: linux
Severity: wishlist
X-Debbugs-Cc: debian-riscv@lists.debian.org
User: debian-riscv@lists.debian.org
Usertags: riscv64

Dear maintainer,

Please enable CMA on riscv64.

  CONFIG_CMA=y
  CONFIG_DMA_CMA=y

This is required on SBCs (e.g. with JH7110 or TH1520) to allocate the framebuffer for normal HD displays at 1920x1080 or higher.
Without this, the display falls back to something like 1024×768 and typically stays black.

I am currently using `cma=128M` on the cmdline which works fine at 1920x1080.

Best
-Dominique

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#92797

Hi Dominique,

On 2026-05-27 13:34, Dominique Belhachemi wrote:
> Source: linux
> Severity: wishlist
> X-Debbugs-Cc: debian-riscv@lists.debian.org
> User: debian-riscv@lists.debian.org
> Usertags: riscv64
> 
> Dear maintainer,
> 
> Please enable CMA on riscv64.
> 
>   CONFIG_CMA=y
>   CONFIG_DMA_CMA=y

Both options got enabled starting with linux 7.1~rc3-1~exp1, currently 
available in experimental. Could you please confirm that it works for 
your use case?

Thanks
Aurelien

-- 
Aurelien Jarno                          GPG: 4096R/1DDD8C9B
aurelien@aurel32.net                     http://aurel32.net

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#92802

On Wed, May 27, 2026 at 3:54 PM Aurelien Jarno <aurel32@debian.org> wrote:
>
> Hi Dominique,
>
> On 2026-05-27 13:34, Dominique Belhachemi wrote:
> > Source: linux
> > Severity: wishlist
> > X-Debbugs-Cc: debian-riscv@lists.debian.org
> > User: debian-riscv@lists.debian.org
> > Usertags: riscv64
> >
> > Dear maintainer,
> >
> > Please enable CMA on riscv64.
> >
> >   CONFIG_CMA=y
> >   CONFIG_DMA_CMA=y
>
> Both options got enabled starting with linux 7.1~rc3-1~exp1, currently
> available in experimental. Could you please confirm that it works for
> your use case?
>
Hi Aurelien,
Thank you, yes it works. I just tested it with 7.1~rc4-1~exp1 on a
VisionFive 2 SBC with additional HDMI patches.
Debian's kernel config uses
    CONFIG_CMA_SIZE_MBYTES=64
which is good enough for two 1920x1080 framebuffers.
For 4K I could simply specify cma=128M on the cmdline.

Best
-Dominique

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#92820

Version: 7.1~rc3-1~exp1

Hi,

On 2026-05-28 00:47, Dominique Belhachemi wrote:
> On Wed, May 27, 2026 at 3:54 PM Aurelien Jarno <aurel32@debian.org> wrote:
> >
> > Hi Dominique,
> >
> > On 2026-05-27 13:34, Dominique Belhachemi wrote:
> > > Source: linux
> > > Severity: wishlist
> > > X-Debbugs-Cc: debian-riscv@lists.debian.org
> > > User: debian-riscv@lists.debian.org
> > > Usertags: riscv64
> > >
> > > Dear maintainer,
> > >
> > > Please enable CMA on riscv64.
> > >
> > >   CONFIG_CMA=y
> > >   CONFIG_DMA_CMA=y
> >
> > Both options got enabled starting with linux 7.1~rc3-1~exp1, currently
> > available in experimental. Could you please confirm that it works for
> > your use case?
> >
> Hi Aurelien,
> Thank you, yes it works. I just tested it with 7.1~rc4-1~exp1 on a
> VisionFive 2 SBC with additional HDMI patches.
> Debian's kernel config uses
>     CONFIG_CMA_SIZE_MBYTES=64
> which is good enough for two 1920x1080 framebuffers.
> For 4K I could simply specify cma=128M on the cmdline.

Thanks for the confirmation. I am therefore closing this bug with that 
version.

Regards
Aurelien

-- 
Aurelien Jarno                          GPG: 4096R/1DDD8C9B
aurelien@aurel32.net                     http://aurel32.net

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#92825 — Bug#1138060: marked as done (riscv64: please enable contiguous memory allocator (CMA) support, needed for HDMI displays)

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Your message dated Thu, 28 May 2026 23:38:59 +0200
with message-id <ahi18_Y19g1sMrDU@aurel32.net>
and subject line Re: Bug#1138060: riscv64: please enable contiguous memory allocator (CMA) support, needed for HDMI displays
has caused the Debian Bug report #1138060,
regarding riscv64: please enable contiguous memory allocator (CMA) support, needed for HDMI displays
to be marked as done.

This means that you claim that the problem has been dealt with.
If this is not the case it is now your responsibility to reopen the
Bug report if necessary, and/or fix the problem forthwith.

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-- 
1138060: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=1138060
Debian Bug Tracking System
Contact owner@bugs.debian.org with problems

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