Re: [PATCH v2 3/3] host/rootfs: Simplify s6-rc dependencies

[Demi Marie Obenour <demiobenour@gmail.com>]

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On 9/25/25 07:07, Alyssa Ross wrote:
> Demi Marie Obenour <demiobenour@gmail.com> writes:
> 
>> This moves almost all of the s6-rc dependencies into named, commented
>> bundles.  This makes the system much easier to understand.
>>
>> Most of the explanation is in the bundle files themselves.
>>
>> Signed-off-by: Demi Marie Obenour <demiobenour@gmail.com>
>> ---
>>  host/rootfs/Makefile                                  |  8 ++++----
>>  host/rootfs/image/etc/s6-rc/basic/contents            | 18 ++++++++++++++++++
>>  host/rootfs/image/etc/s6-rc/{vmm-env => basic}/type   |  0
>>  .../image/etc/s6-rc/{vmm-env => basic}/type.license   |  0
>>  host/rootfs/image/etc/s6-rc/ok-all/contents           | 19 ++++++++++++++++---
>>  .../s6-rc/sys-vmms/dependencies.d/{vmm-env => vm-env} |  0
>>  host/rootfs/image/etc/s6-rc/systemd-udevd/run         |  9 ++++++---
>>  host/rootfs/image/etc/s6-rc/vm-env/contents           | 13 ++++++++++---
>>  host/rootfs/image/etc/s6-rc/vmm-env/contents          |  9 ---------
>>  .../dependencies.d/{systemd-udevd-coldplug => basic}  |  0
>>  10 files changed, 54 insertions(+), 22 deletions(-)
> 
> Hmm, we just moved away from using dependencies files to dependencies.d
> directories, but now we're going the other way with contents?  That's
> not to say we couldn't have a README file in each contents.d or
> something serving much the same purpose, though.

I did not know that contents.d was supported.
Will fix once the systemd-udevd work has landed.

>> diff --git a/host/rootfs/image/etc/s6-rc/basic/contents b/host/rootfs/image/etc/s6-rc/basic/contents
>> new file mode 100644
>> index 0000000000000000000000000000000000000000..54f58577ba9f125e7fc08dcdd69394e8a88ab622
>> --- /dev/null
>> +++ b/host/rootfs/image/etc/s6-rc/basic/contents
>> @@ -0,0 +1,18 @@
>> +# SPDX-License-Identifier: CC0-1.0
>> +# SPDX-FileCopyrightText: 2021 Alyssa Ross <hi@alyssa.is>
>> +# SPDX-FileCopyrightText: 2025 Demi Marie Obenour <demiobenour@gmail.com>
>> +
>> +# This file contains all atomics and bundles needed for basic system
>> +# initialization.  Everything that is not meant to run in early boot
>> +# should depend on this.
>> +
>> +# This ensures that core files are written to the right place.
>> +core
>> +
>> +# This ensures that static nodes are created.
>> +static-nodes
>> +
>> +# systemd runs systemd-udev-trigger.service before sysinit.target.
>> +# Therefore, anything using libudev that isn't an early boot service
>> +# might expect udev coldplug to have finished.
>> +systemd-udevd-coldplug
> 
> I'm not convinced by the "basic" bundle.  I worry that it's likely to
> end up accumulating stuff that isn't actually needed by everything that
> depends on it, and that things will end up being slow because they're
> waiting for things they don't actually need.  I'm not sure where core
> should go, really, because anything /could/ crash at any time.
> static-nodes is presumably going away anyway with udev, so this is
> really just the coldplug bundle.

static-nodes isn't going away.

>> diff --git a/host/rootfs/image/etc/s6-rc/ok-all/contents b/host/rootfs/image/etc/s6-rc/ok-all/contents
>> index c76a5af336c7f1c3f4b81bf1f6244a53e0399fe8..edef03d2b6eae4fb0b92ac828436cd4572ca7acc 100644
>> --- a/host/rootfs/image/etc/s6-rc/ok-all/contents
>> +++ b/host/rootfs/image/etc/s6-rc/ok-all/contents
>> @@ -1,6 +1,19 @@
>>  # SPDX-License-Identifier: CC0-1.0
>>  # SPDX-FileCopyrightText: 2021 Alyssa Ross <hi@alyssa.is>
>> -#
>> -systemd-udevd-coldplug
>> +# SPDX-FileCopyrightText: 2025 Demi Marie Obenour <demiobenour@gmail.com>
>> +
>> +# This file contains the services that need to be started even
>> +# if nothing else depends on them.  It should not include services
>> +# that are only needed by other services.  For instance, it would
>> +# not be appropriate for this file to reference systemd-udevd.
>> +# However, services should be included in this file whenever they
>> +# are directly needed by the user, even if they depend on another
>> +# service in this files.  For instance, sys-vmms depends on weston,
>> +# but it is still included.
>> +
>> +# VMMs that should be started at boot.  In the future
>> +# it might make sense to start them only as needed.
>>  sys-vmms
>> -vm-env
> 
> See below — I think the name of "vm-env" hasn't captured what it does
> very well.
> 
>> diff --git a/host/rootfs/image/etc/s6-rc/systemd-udevd/run b/host/rootfs/image/etc/s6-rc/systemd-udevd/run
>> index 2501680b69eb0060b651146dffb6b3a99640c6fb..f05804a6b3903a767f8e1400cf0153045dd3781f 100644
>> --- a/host/rootfs/image/etc/s6-rc/systemd-udevd/run
>> +++ b/host/rootfs/image/etc/s6-rc/systemd-udevd/run
>> @@ -1,11 +1,14 @@
>>  #!/bin/execlineb -P
>>  # SPDX-License-Identifier: EUPL-1.2+
>>  # SPDX-FileCopyrightText: 2025 Demi Marie Obenour <demiobenour@gmail.com>
>> -if { rm -f /run/sd-notify-wrapper/systemd-udevd }
>> +if { mkdir -p /run/sd-notify-wrapper }
>> +s6-setlock -d 4 /run/sd-notify-wrapper/systemd-udevd.lock
>> +if { rm -f /run/sd-notify-wrapper/systemd-udevd.sock }
>>  background {
>> -   s6-ipcserver-socketbinder -b0 -m -a 0600 /run/sd-notify-wrapper/systemd-udevd
>> +   s6-ipcserver-socketbinder -b0 -m -a 0600 /run/sd-notify-wrapper/systemd-udevd.sock
>>     fdmove 1 3
>>     sd-notify-adapter
>>  }
>> -export NOTIFY_SOCKET /run/sd-notify-wrapper/systemd-udevd
>> +fdclose 3
>> +export NOTIFY_SOCKET /run/sd-notify-wrapper/systemd-udevd.sock
>>  exec -a systemd-udevd udevadm
> 
> Are these changes supposed to be here?

No, they are not. 

>> diff --git a/host/rootfs/image/etc/s6-rc/vm-env/contents b/host/rootfs/image/etc/s6-rc/vm-env/contents
>> index ed8b5c410adfc17f5bbc33932ac79d97bd7b3115..81bfd422d22bde582fe198e0778c1c93d0d0f329 100644
>> --- a/host/rootfs/image/etc/s6-rc/vm-env/contents
>> +++ b/host/rootfs/image/etc/s6-rc/vm-env/contents
>> @@ -1,6 +1,13 @@
>>  # SPDX-License-Identifier: CC0-1.0
>>  # SPDX-FileCopyrightText: 2021 Alyssa Ross <hi@alyssa.is>
>> -#
>> -static-nodes
>> -systemd-udevd-coldplug
>> +# SPDX-FileCopyrightText: 2025 Demi Marie Obenour <demiobenour@gmail.com>
>> +
>> +# This file contains s6 atomics and bundles that
>> +# need to be started before starting any VMs.
>> +
>> +# Basic initialization
>> +basic
>> +# KVM being available
>> +kvm
>> +# Wayland compositor ready
>>  weston
>> diff --git a/host/rootfs/image/etc/s6-rc/vmm-env/contents b/host/rootfs/image/etc/s6-rc/vmm-env/contents
>> deleted file mode 100644
>> index 9a1aea63abd1b5c374e3ac9a9671e4c9341f8d16..0000000000000000000000000000000000000000
>> --- a/host/rootfs/image/etc/s6-rc/vmm-env/contents
>> +++ /dev/null
>> @@ -1,9 +0,0 @@
>> -# SPDX-License-Identifier: CC0-1.0
>> -# SPDX-FileCopyrightText: 2021 Alyssa Ross <hi@alyssa.is>
>> -#
>> -core
>> -kvm
>> -# systemd runs systemd-udev-trigger.service before sysinit.target.
>> -# Therefore, anything using libudev that isn't an early boot service
>> -# might expect udev coldplug to have finished.
>> -systemd-udevd-coldplug
> 
> I think it probably makes sense to keep a distinction between "user can
> now start VMs" (vm-env) and "it is now possible to start a VMM, possibly
> automatically" (vmm-env).  We can of course try to find better names,
> though.

can-start-vms-automatically and can-start-vms-manually?
-- 
Sincerely,
Demi Marie Obenour (she/her/hers)

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