[Buildroot] [PATCH] tvheadend: add dependency on udev based rootfs creation

[daggs]

Greetings Thomas,

> Sent: Friday, December 29, 2017 at 4:03 PM
> From: "Thomas Petazzoni" <thomas.petazzoni at free-electrons.com>
> To: daggs <daggs at gmx.com>
> Cc: buildroot at buildroot.org, "Bernd Kuhls" <bernd.kuhls at t-online.de>
> Subject: Re: [Buildroot] [PATCH] tvheadend: add dependency on udev based rootfs creation
>
> Hello,
> 
> On Fri, 29 Dec 2017 14:57:59 +0100, daggs wrote:
> 
> > > You should use BR2_PACKAGE_HAS_UDEV instead. Indeed udev can be
> > > provided by either eudev or systemd.  
> > does using BR2_PACKAGE_HAS_UDEV means rootfs dev creation will use udev?
> 
> config BR2_PACKAGE_EUDEV
>         bool "eudev"
>         depends on BR2_ROOTFS_DEVICE_CREATION_DYNAMIC_EUDEV
>         depends on BR2_USE_MMU # uses fork()
>         depends on BR2_USE_WCHAR # needs C99 compiler
>         depends on !BR2_STATIC_LIBS # kmod
>         select BR2_PACKAGE_HAS_UDEV
> 
> So for the eudev case, BR2_PACKAGE_HAS_UDEV is selected when eudev is
> enabled, and eudev can only be enabled when
> BR2_ROOTFS_DEVICE_CREATION_DYNAMIC_EUDEV is enabled.
> 
> For the systemd case:
> 
> menuconfig BR2_PACKAGE_SYSTEMD
>         bool "systemd"
>         depends on BR2_INIT_SYSTEMD
>         depends on !BR2_STATIC_LIBS # kmod
>         depends on BR2_TOOLCHAIN_HAS_THREADS # dbus
>         depends on BR2_USE_MMU # dbus
>         select BR2_PACKAGE_HAS_UDEV
> 
> So BR2_PACKAGE_HAS_UDEV is selected when systemd is enabled, which is
> only possible when systemd is the init system.
> 
> Bottom line: as soon as systemd is the init system *or* eudev is used
> at the dev management method, you are guaranteed that
> BR2_PACKAGE_HAS_UDEV=y.
ok, I'll look into it.

> 
> > > Also, does tvheadend needs to link with libudev ? If so, it should have
> > > udev in its <pkg>_DEPENDENCIES. If it doesn't link with libudev, then
> > > I'm not sure to see how udev helps for tvheadend to detect USB DVB
> > > cards.  
> > it doesn't, frankly I don't understand it too, I'm wrestling this for 3 weeks now, without udev, tvheadend didn't listed my adapter in the webui.
> > on the desktop it did, after some thinking I've decided to try building udev and it worked.
> > maybe Bernd might have some ideas on the matter. 
> 
> This is a somewhat weak understanding of what's happening here. I think
> we need a better understanding of what's going on rather than
> more-or-less randomly adding a dependency.
for that I need either time to look into the code or an answer from the devs, time I don't have unfortunately, devs aren't responding yet.
I encountered the issue and was able to get it to work, I assume that others might have seen it and didn't had time to look into it.
also as said, maybe Bernd knows what is the issue here and can propose a better fix.

Dagg.