On 23 May 2014 14:41, "Ian Campbell" ijc@hellion.org.uk wrote:
On Fri, 2014-05-23 at 06:44 +0800, Andy Green wrote:
On 22 May 2014 22:49, Ian Campbell ijc@hellion.org.uk wrote:
On Thu, 2014-05-22 at 20:52 +0800, Andy Green wrote:
On 22 May 2014 17:50, Ian Campbell ijc@hellion.org.uk wrote:
On Wed, 2014-05-21 at 14:39 +0300, Riku Voipio wrote:
Hi,
I've collected a list of where people install their dtb files
these
days;
https://wiki.linaro.org/Platform/DeviceTreeConsolidation
Every distribution has a slightly different variation of install location, which is not good - we can't tell end users that "this
is
the place you can expect to find your device tree files
regardless of
what distribution you choose". Some questions I have here before
we
proceed discussing what would be the standardized location:
- Anything missing of the pros and cons of different locations?
FWIW Debian will now arrange for the correct DTB for the platform
to be
installed as /boot/dtb-$(uname -r) as well as the /usr/lib
location.
...
I'm more or less ambivalent about installing all of the possible
DTB
files in a similar location though. I'm not sure what the use case
for
that is. Wouldn't you also need to standardise on the dtb filename
for
each platform and effectively make that ABI?
For installs on eg, an SD Card, there's nothing stopping the one SD Card being usable on multiple different SoC platforms if the bootloader will allow it.
For example Fujitsu have various SoC with bootloader in HSSPI NOR, which knows the right dtb filename for that SoC.
So if all the dtbs are in /boot/whatever, that same SD Card is
capable
to boot on any of them, since they're all supported by the same
single
kernel binary from the same SD Card, and the bootloader picked out
the
right one for what it happens to be running on. It's very
convenient.
But such an sd card would only work on these Fujitsu SoCs, wouldn't
it?
No... if you consider "multi_v7_defconfig" in mainline that one kernel binary is supporting
I know this.
What I meant was that the boot script on the sd card would be assuming that the bootloader was the Fujitsu one which "knows the right dtb filename for that SoC", and hence would only work on those systems. Unless this knowledge of the right dtb name is to become a standard
No, as I wrote those systems have a board-specific bootloader on the board, not the OS media, that knows the correct dtb name for the board. There is no 'boot script on the SD card' needed for these kind of SoC.
That setup just requires a standard dir to find the already known dtb filename in and it can boot any OS that put the things in the right places.
Something will need to suggest which kernel to use in multi-kernel case, a symlink would do.
Otherwise it can work on any sd card image for, eg one aimed at uboot and the v7 defconfig, it'll just ignore the uboot bits, grab the right dtb and the kernel from the standard place on the sd card and boot.
-Andy
also...
In which case a single boot.scr could equally well handle it.
...
Or is there a separate effort to standardise uboot bootcmd settings as well?
As Stephen says, a few weeks ago I installed Fedora 20 on a Cubiebrick for my own web services, I noticed there is a monster U-Boot script coming with Fedora now that is trying to normalize U-Boot across all the boards (a pretty amazing endeavour actually).
... which it sounds like it might be.
How do other OSes call their DTB files? I expect they aren't consistent with Linux...
Ian.