Re: [DistroKit] [PATCH 1/8] rauc-udev: add a compatibility layer for mapping partitions

[Roland Hieber <rhi@pengutronix.de>]

On Mon, Feb 13, 2023 at 10:43:43AM +0100, Michael Olbrich wrote:
> On Sun, Feb 12, 2023 at 11:14:42PM +0100, Roland Hieber wrote:
> > When we add RAUC support for different platforms later, we need a way to
> > specify their respective root partitions in RAUC's system.conf; however,
> > the names of the actual partitions can differ on different hardware
> > platforms. Add a short udev rule that can add symlinks to the actual
> > partitions based on the device tree compatible. This way we can refer to
> > the partitions in system.conf using the symlinks on all boards that we
> > want to support.
> > 
> > This commit only adds a stub for now; we will add the code that creates
> > the actual symlinks for each hardware in later commits.
> > 
> > Signed-off-by: Roland Hieber <rhi@pengutronix.de>
> > ---
> >  configs/ptxconfig                             |  1 +
> >  projectroot/usr/lib/udev/of_base_compatible   |  4 ++
> >  .../lib/udev/rules.d/90-rauc-partitions.rules | 12 ++++++
> >  rules/rauc-udev.in                            |  8 ++++
> >  rules/rauc-udev.make                          | 37 +++++++++++++++++++
> >  5 files changed, 62 insertions(+)
> >  create mode 100755 projectroot/usr/lib/udev/of_base_compatible
> >  create mode 100644 projectroot/usr/lib/udev/rules.d/90-rauc-partitions.rules
> >  create mode 100644 rules/rauc-udev.in
> >  create mode 100644 rules/rauc-udev.make
> > 
> > diff --git a/configs/ptxconfig b/configs/ptxconfig
> > index 3c8c001aaf8e..a6a3f29afb53 100644
> > --- a/configs/ptxconfig
> > +++ b/configs/ptxconfig
> > @@ -3,6 +3,7 @@
> >  # PTXdist 2022.12.0
> >  #
> >  PTXCONF_DATAPARTITION=y
> > +PTXCONF_RAUC_UDEV=y
> >  
> >  #
> >  # ------------------------------------
> > diff --git a/projectroot/usr/lib/udev/of_base_compatible b/projectroot/usr/lib/udev/of_base_compatible
> > new file mode 100755
> > index 000000000000..6b59c9cc569d
> > --- /dev/null
> > +++ b/projectroot/usr/lib/udev/of_base_compatible
> > @@ -0,0 +1,4 @@
> > +#!/bin/sh
> > +# SPDX-License-Identifier: 0-BSD
> > +# SPDX-FileCopyrightText: 2021 Roland Hieber, Pengutronix <rhi@pengutronix.de>
> > +printf 'OF_BASE_COMPATIBLE="%s"\n' "$(xargs -0  printf "%s " < /sys/firmware/devicetree/base/compatible)"
> 
> This seems overly complicated. Why do you need xargs and two printf here?

Hmmm yes. In udev I'm matching for *string* anyways. So my current,
simpler, working version is:

  printf 'OF_BASE_COMPATIBLE="%s"\n' "$(tr '\0' ' ' < /sys/firmware/devicetree/base/compatible)"

(Turns out, busybox's sed cannot cope with null bytes at all…)

 - Roland

> Michael
> 
> > diff --git a/projectroot/usr/lib/udev/rules.d/90-rauc-partitions.rules b/projectroot/usr/lib/udev/rules.d/90-rauc-partitions.rules
> > new file mode 100644
> > index 000000000000..0300e8b9daad
> > --- /dev/null
> > +++ b/projectroot/usr/lib/udev/rules.d/90-rauc-partitions.rules
> > @@ -0,0 +1,12 @@
> > +# SPDX-License-Identifier: 0-BSD
> > +# SPDX-FileCopyrightText: 2021 Roland Hieber, Pengutronix <rhi@pengutronix.de>
> > +
> > +ACTION=="remove", GOTO="rauc_partitions_end"
> > +SUBSYSTEM!="block", GOTO="rauc_partitions_end"
> > +
> > +IMPORT{program}="of_base_compatible"
> > +
> > +# Add symlinks named /dev/disk/by-usage/{data,rootfs0,rootfs1} pointing
> > +# to the correct partitions based on the device tree compatible
> > +
> > +LABEL="rauc_partitions_end"
> > diff --git a/rules/rauc-udev.in b/rules/rauc-udev.in
> > new file mode 100644
> > index 000000000000..4e90343ba2dc
> > --- /dev/null
> > +++ b/rules/rauc-udev.in
> > @@ -0,0 +1,8 @@
> > +## SECTION=project_specific
> > +
> > +config RAUC_UDEV
> > +	tristate
> > +	prompt "rauc udev rules"
> > +	select UDEV if RUNTIME
> > +	help
> > +	  udev rules for cross-hardware-compatible partition symlinks
> > diff --git a/rules/rauc-udev.make b/rules/rauc-udev.make
> > new file mode 100644
> > index 000000000000..6a806fc43e34
> > --- /dev/null
> > +++ b/rules/rauc-udev.make
> > @@ -0,0 +1,37 @@
> > +# -*-makefile-*-
> > +#
> > +# Copyright (C) 2021 by Roland Hieber, Pengutronix <rhi@pengutronix.de>
> > +#
> > +# For further information about the PTXdist project and license conditions
> > +# see the README file.
> > +#
> > +
> > +#
> > +# We provide this package
> > +#
> > +PACKAGES-$(PTXCONF_RAUC_UDEV) += rauc-udev
> > +
> > +RAUC_UDEV_VERSION	:= 1
> > +RAUC_UDEV_LICENSE	:= 0-BSD
> > +
> > +# ----------------------------------------------------------------------------
> > +# Target-Install
> > +# ----------------------------------------------------------------------------
> > +
> > +$(STATEDIR)/rauc-udev.targetinstall:
> > +	@$(call targetinfo)
> > +
> > +	@$(call install_init, rauc-udev)
> > +	@$(call install_fixup,rauc-udev,PRIORITY,optional)
> > +	@$(call install_fixup,rauc-udev,SECTION,base)
> > +	@$(call install_fixup,rauc-udev,AUTHOR,"Roland Hieber, Pengutronix <rhi@pengutronix.de>")
> > +	@$(call install_fixup,rauc-udev,DESCRIPTION,missing)
> > +
> > +	@$(call install_alternative, rauc-udev, 0, 0, 0755, /usr/lib/udev/of_base_compatible)
> > +	@$(call install_alternative, rauc-udev, 0, 0, 0644, /usr/lib/udev/rules.d/90-rauc-partitions.rules)
> > +
> > +	@$(call install_finish,rauc-udev)
> > +
> > +	@$(call touch)
> > +
> > +# vim: syntax=make
> > -- 
> > 2.30.2
> > 
> > 
> > 
> 
> -- 
> Pengutronix e.K.                           |                             |
> Steuerwalder Str. 21                       | http://www.pengutronix.de/  |
> 31137 Hildesheim, Germany                  | Phone: +49-5121-206917-0    |
> Amtsgericht Hildesheim, HRA 2686           | Fax:   +49-5121-206917-5555 |
> 
> 

-- 
Roland Hieber, Pengutronix e.K.          | r.hieber@pengutronix.de     |
Steuerwalder Str. 21                     | https://www.pengutronix.de/ |
31137 Hildesheim, Germany                | Phone: +49-5121-206917-0    |
Amtsgericht Hildesheim, HRA 2686         | Fax:   +49-5121-206917-5555 |