[U-Boot] MULTI_DTB_FIT_GZIP

[U-Boot] MULTI_DTB_FIT_GZIP

[Tim Harvey]

Greetings,

I'm working on converting IMX6 based Gateworks Ventana board support
to DM which requires me to put many dtb's (36 currently!) into a FIT
image. The size of the FIT image has grown to 2MiB more than 2x the
size of u-boot-notdtb.bin so I want to use compression.

It appears that MULTI_DTB_FIT_GZIP compresses the entire FIT image. In
my case fit-dtb.blob is 1.4MiB and fit-dtb.blob.gz compresses to
289KiB which is good. There's no way I'll be able to use
SPL_MULTI_DTB_FIT with all those dtbs while supporting imx6s/dl with
only 128K of SRAM so I'm using the U-Boot flavor of MULTI DTB
(SPL_LOAD_FIT and MULTI_DTB_FIT).

I'm not clear exactly how to take advantage of fit-dtb.blob.gz as
u-boot.img has the uncompressed fit image. I'm currently flashing
u-boot-dtb.img to my board and its processing the FIT and booting
properly but u-boot-dtb.img does not have a compressed FIT.

Is there some support missing for using MULTI_DTB_FIT_GZIP/LZO with a
fit image in U-Boot vs the SPL?

Best regards,

Tim

[U-Boot] MULTI_DTB_FIT_GZIP

[Simon Goldschmidt]

Am 19.11.2019 um 18:39 schrieb Tim Harvey:
> Greetings,
> 
> I'm working on converting IMX6 based Gateworks Ventana board support
> to DM which requires me to put many dtb's (36 currently!) into a FIT
> image. The size of the FIT image has grown to 2MiB more than 2x the
> size of u-boot-notdtb.bin so I want to use compression.

Have you thought about using DT overlays? Maybe that could also bring 
the binary size down?

Regards,
Simon

> 
> It appears that MULTI_DTB_FIT_GZIP compresses the entire FIT image. In
> my case fit-dtb.blob is 1.4MiB and fit-dtb.blob.gz compresses to
> 289KiB which is good. There's no way I'll be able to use
> SPL_MULTI_DTB_FIT with all those dtbs while supporting imx6s/dl with
> only 128K of SRAM so I'm using the U-Boot flavor of MULTI DTB
> (SPL_LOAD_FIT and MULTI_DTB_FIT).
> 
> I'm not clear exactly how to take advantage of fit-dtb.blob.gz as
> u-boot.img has the uncompressed fit image. I'm currently flashing
> u-boot-dtb.img to my board and its processing the FIT and booting
> properly but u-boot-dtb.img does not have a compressed FIT.
> 
> Is there some support missing for using MULTI_DTB_FIT_GZIP/LZO with a
> fit image in U-Boot vs the SPL?
> 
> Best regards,
> 
> Tim
> _______________________________________________
> U-Boot mailing list
> U-Boot at lists.denx.de
> https://lists.denx.de/listinfo/u-boot
> 

[U-Boot] MULTI_DTB_FIT_GZIP

[Tim Harvey]

On Tue, Nov 19, 2019 at 12:32 PM Simon Goldschmidt
<simon.k.r.goldschmidt@gmail.com> wrote:
>
> Am 19.11.2019 um 18:39 schrieb Tim Harvey:
> > Greetings,
> >
> > I'm working on converting IMX6 based Gateworks Ventana board support
> > to DM which requires me to put many dtb's (36 currently!) into a FIT
> > image. The size of the FIT image has grown to 2MiB more than 2x the
> > size of u-boot-notdtb.bin so I want to use compression.
>
> Have you thought about using DT overlays? Maybe that could also bring
> the binary size down?

Simon,

That's an interesting idea and something that I definitely will need
in the near future for an IMX8 product family we are working on that
will marry a SOM module with a baseboard in which case I will want to
use overlays for each.

I could use that now by wrapping the imx6dl.dtsi and imx6q.dtsi into
overlays as those are likely the bulk of my dts's. Is there any
overlay support currently? What are the boards that are using SOM
modules doing? What are boards such as beaglebone doing with the 'hat'
modules?

Ultimately I do want to see the compressed fit image working as that's
likely going to just improve the situation regardless of how many
dtb's you have.

Thanks,

Tim