From mboxrd@z Thu Jan 1 00:00:00 1970 From: Yann E. MORIN Date: Mon, 13 Jun 2016 22:00:03 +0200 Subject: [Buildroot] [PATCH] package/systemd: Optionally disable hwdb In-Reply-To: References: <1460717190-29291-1-git-send-email-m.niestroj@grinn-global.com> <20160608201910.GA3694@free.fr> Message-ID: <20160613200003.GA3786@free.fr> List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: buildroot@busybox.net 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. -- .-----------------.--------------------.------------------.--------------------. | Yann E. MORIN | Real-Time Embedded | /"\ ASCII RIBBON | Erics' conspiracy: | | +33 662 376 056 | Software Designer | \ / CAMPAIGN | ___ | | +33 223 225 172 `------------.-------: X AGAINST | \e/ There is no | | http://ymorin.is-a-geek.org/ | _/*\_ | / \ HTML MAIL | v conspiracy. | '------------------------------^-------^------------------^--------------------'