[Buildroot] [PATCH] package/systemd: Optionally disable hwdb

[Yann E. MORIN <yann.morin.1998@free.fr>]

Marcin, All,

On 2016-06-13 11:20 +0200, Marcin Niestroj spake thusly:
> On 08.06.2016 22:19, Yann E. MORIN wrote:
> >On 2016-04-15 12:46 +0200, Marcin Niestroj spake thusly:
> >>By default hwdb files are installed in /usr/lib/udev/hwdb.d
> >>Currently they take about ~5MB. After first boot, systemd-hwdb tool
> >>parses them and creates a binary in /etc/udev/hwdb.bin, which takes
> >>another ~6.5MB.
> >>
> >>In case of initramfs images, hwdb parsing is done every boot. This adds
> >>about 2-3 seconds to boot time in case of rootfs on SDHC class 10
> >>card (benchmarked with am335x board). NAND boot takes even longer.
[--SNIP--]
> >Yet, I'd like to know what would be the impact of not having hwdb
> >support at runtime. Care to shed some light, please?
> 
> HWDB is mainly a database of device classes and vendors (for PCI, SDIO,
> USB). This is helpfull during development, because tools like lsusb are
> able to show vendor and usb class for each device. However we don't
> need this in production most of the time.
> Additionally there are some files for input devices, like mouse,
> keyboard and pointstick. In keyboard files for example there are
> defined some special keys, like play/pause, volumeup etc.

OK, thanks for the info, definitively usefull.

So, it seems this is not systematically needed on production systems,
but mostly a "debugging" aid in most cases. And for those that need it,
it's still an option.

However, people that do need it and that are working either on a
read-only filesystem or a transient one (initramfs) would need a mean
to avoid building this hwdb at every boot... That would be so cool...

Regards,
Yann E. MORIN.

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