Hi Tom,
On 22/6/20 12:25, Walter Lozano wrote:
Hi Tom,
On 22/6/20 11:20, Tom Rini wrote:
On Mon, Jun 22, 2020 at 11:12:40AM -0300, Walter Lozano wrote:
Hi Tom,
On 19/6/20 18:48, Tom Rini wrote:
On Fri, Jun 19, 2020 at 06:11:36PM -0300, Walter Lozano wrote:
Based on several reports and discussions it is clear that U-Boot's
footprint is always a concern, and any kind of reduction is an
improvement.
This series is a proposal to help reducing the footprint by parsing
information provided in DT and drivers in different ways and adding
additional intelligence to dtoc. The current version implements
the basic
functionality in dtoc but this is no fully integrated, however it
will allow
us to discuss this approach.
Firstly, based on the compatible strings found in drivers, include
only DT nodes
which are supported by any driver present in U-Boot.
Secondly, generate struct udevice_id entries only for nodes
present in DT,
which will allow to avoid including additional data.
These are the first steps for further improvements as proposed in
the specific
patches in this series.
This work is based on the work of Simon Glass present in [1] which
adds
support to dtoc for parsing compatible strings.
[1]
https://gitlab.denx.de/u-boot/custodians/u-boot-dm/-/tree/dtoc-working
I applied this series on top of the above tree, but there's no rule
for
<generated/compatible.h> so is something missing? Thanks!
Thanks for taking the time to check this RFC.
As you pointed, the Makefile needs to be tweaked in order to be able
to run
a build, that is what I meant by "not fully integrated", also some
additional stuff are missing. However, I thought that sending this RFC
explaining the idea will be nice in order to confirm if the approaches
proposed make sense for the community and at least the one to handle
compatible strings is different from the linker list suggestion.
I think I like the idea, but I need to give a build a spin and poke
things harder. What do I need to do to manually have this build+link?
Thanks!
Well, I don't think this version will give you something to fully
test, as there are several pieces missing, but the fact you think you
like the idea is good starting point.
Just to do some testing you can try
Shrink a dtb with
./tools/dtoc/dtoc shrink -d u-boot.dtb
this will shrink u-boot.dtb and create u-boot-shrink.dtb by only
include nodes with compatible strings present in drivers
Generate include/generated/compatible.h
./tools/dtoc/dtoc compatible -d u-boot.dtb -o
include/generated/compatible.h
this will generate compatible.h but the code does not yet support
struct udevice_id with data in struct udevice_id and does not filter
anything.
I will continue working on these features but any early feedback is
welcome.
To be able to test this a bit more I reworked and back ported the
patches and add a bit more of work on top, such as
- Add Makefile rules (need to be improved)
- Add support for checking enabled drivers for dtb shrink (need to be
improved as parsing probably does not take into account no common
situations)
- Add support for defining constants based on compatible strings enabled
This work can be found in
https://gitlab.collabora.com/wlozano/u-boot/-/tree/wip
The drawback is that this implementation doesn't take advantage of the
new abstractions found in the Simon's work, but I think it could still
be useful to test the idea, and discuss if it makes sense.
I have done some testing in my iMX6 Hummingboard but I have found some
issues not related to this work in MMC, which I need to debug.
Regards,
Walter
