Hi,
On 13-04-15 23:25, Paul Kocialkowski wrote:
Le lundi 13 avril 2015 à 22:25 +0200, Maxime Ripard a écrit :
On Mon, Apr 13, 2015 at 09:30:53PM +0200, Hans de Goede wrote:
Hi,
On 13-04-15 17:50, Paul Kocialkowski wrote:
After working a bit on sunxi recently, I found myself somewhat puzzled
with the ways sunxi devices are named in mainstream U-Boot, mainstream
Linux (device-tree), sunxi-boards and the linux-sunxi wiki. What bothers
me particularly is the lack of consistency across those projects and
among devices. This is clearly not a technical topic of interest, but
all that disparity and lack of consistency is starting to annoy me a
lot.
Currently, there are apparently no guidelines (or nobody cares to
respect or enforce them) on most of those projects. I would like to
discuss this problem with the maintainers of each of those so that we
could find a common and consistent way of naming sunxi devices, convert
the already supported devices to comply with the new naming scheme and
stick to it in the future. I know that a fair share of people just don't
care about it, but I hope that the maintainers for those projects will
see some interest in it.
First off, such a change will probably mess up a few hand-written build
scripts and bother a few people at first, but I think it's better to do
it now instead of waiting or not doing anything about it.
To summarize, the current situation varies a bit depending on each
project:
U-Boot:
* Defconfig targets allow the use of upper-case, lower-case, dashes and
underscores
* Most targets follow the following scheme: [Vendor]_[Model]_defconfig
* Some targets do not respect the vendor or model typography
(A20-Olinuxino-Lime2 is not correct for the model part, it should be
A20-Olinuxino-LIME2)
* Some targets use dashes to mark spaces in either the vendor or model
part
* Some devices add prefixes to the configs
Linux:
* Device-tree sources have a clear naming scheme,
a[xx]-sun[x]i-[device].dts, that only allows lower-case and dashes
* However, what [device] is is unclear and sometimes includes the vendor
name, sometimes not
sunxi-boards:
* FEX files are all lower-case and allow dashes and underscores
* There is no clear scheme for the naming of devices, some files include
the vendor name, some don't
* Some files use dashes to mark spaces in either the vendor or model
part
linux-sunxi wiki:
* The scheme to follow should be [Vendor]_[Model] and upper-case,
lower-case, dashes and underscores are allowed
* Some pages may not respect that convention
* Some targets do not respect the vendor or model typography
(A20-Olinuxino-Lime2 is not correct for the model part, it should be
A20-Olinuxino-LIME2)
* Some targets use dashes to mark spaces in either the vendor or model
part
My proposal to unify all this is the following:
* linux-sunxi wiki: use the [Vendor]_[Model] convention while respecting
the correct typography for the vendor and model names (as defined by the
vendor) and using underscores for spaces
* Use exactly the same name for the U-Boot configs, except in the case
mediawiki automatically adds an upper case at the beginning of the page
name (iNet becomes INet but we should still use iNet in the U-Boot
config)
* Use that name with all underscores replaced by dashes and all caps
changed to lower-case in the Linux device-tree names
* Use that name with all caps changed to lower-case in sunxi-boards
I am willing to submit patches for each projects and update the wiki
pages for each concerned device following this convention. Especially, I
would need Maxime's approval for the Linux part, Hans and/or Ian's
approval for U-Boot and an overal feeling of approval for the wiki and
sunxi-boards parts.
Please let me know what you think about all this!
So my 2 cents on this are:
I guess it was 3 cents ? ;)
1) The dts file name is an ABI between u-boot and the kernel and as such
cannot be changed for existing boards. But coming up with and documenting
some standards for new boards may be a good idea.
I never thought of the DTS filename, but I guess that's true,
especially if we don't consider the DT bindings themselves as an ABI
(even though that starts to backfire a bit), since we have to at least
provide some consistency to the downstream users.
Well to be fair here, we know that only U-Boot is using device-tree on
sunxi, so I doubt changing the names of a handful of dts files will
break anything for anyone.
Actually it will, the u-boot binary contains the name of the dtb
to use, and most distro boot configs (extlinux.conf) use this
to load the right dtb. So if we start renaming dtb files,
then as soon as the user installs a kernel upgrade (e.g.
via a simple apt-get update) his board will no longer boot.
This is simply a hard ABI, no discussion possible. If we break this for
rhen we will break peoples boards, and we better have a very good reason
for doing so, not a minor cosmetic one.
> I understand the point though, that it can be
seen as an ABI (don't break the ABI), but it would be a shame for us to
this as a pretext to not correct our mistake.
Don't get me wrong, I don't like breaking ABIs more than the next guy
(even though I fear Hans is starting to think this is becoming kind of
habit for me), but this is really borderline.
Nothing borderline about it, take a standard Fedora or Debian image,
both of which rely on the dtb name embedded in the u-boot binary,
change the dtb name in the kernel, upgrade the kernel, try to boot,
and voila the board will not boot (and no the old dtb file will not
help, as each kernel build has its own dir with dtb files).
Really this is as hard an ABI as one can get, please do not break it.
Regards,
Hans
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