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raspberry_pi:os_adjustments [2017/03/18 20:55]
matthias created
raspberry_pi:os_adjustments [2017/07/07 09:05] (current)
matthias added some details about building an image
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   - (Kernel) ''​vm.dirty_background_ratio = 50''​ & ''​vm.dirty_ratio = 80''​. This Option makes more use of available ram to store written pages. On the one hand, it does increase write speed and the SD card is used more consolidated then with smaller high frequent IO. If 50% free memory is used with written pages, a background tasks starts to write the data to disk. At 80% the system starts to do "​blocking writes",​ which is more like a "​hanging"​ task.    - (Kernel) ''​vm.dirty_background_ratio = 50''​ & ''​vm.dirty_ratio = 80''​. This Option makes more use of available ram to store written pages. On the one hand, it does increase write speed and the SD card is used more consolidated then with smaller high frequent IO. If 50% free memory is used with written pages, a background tasks starts to write the data to disk. At 80% the system starts to do "​blocking writes",​ which is more like a "​hanging"​ task. 
   - (Kernel) ''​vm.dirty_expire_centisecs = 30000''​ (5 minutes) is default value is '​3000'​ which is 30s. This means a page is written to disk latest after ''​vm.dirty_expire_centisecs''​. **This means that a powered off PirateBox will loose data which is up to 5 Minutes old.**   - (Kernel) ''​vm.dirty_expire_centisecs = 30000''​ (5 minutes) is default value is '​3000'​ which is 30s. This means a page is written to disk latest after ''​vm.dirty_expire_centisecs''​. **This means that a powered off PirateBox will loose data which is up to 5 Minutes old.**
 +
 +====== Building a custom images ======
 +The generated images are automatically build by a build chain. You can find it on the corresponding Github repository [[https://​github.com/​PirateBox-Dev/​arch_rpi_image_prepare|arch_rpi_image_prepare]]. The image is prepared via a Makefile following the [[https://​archlinuxarm.org/​platforms/​armv8/​broadcom/​raspberry-pi-3|original steps]]. The customization is done with the scripts in the "​chroot"​-folder. These contain the following steps:
 +  * Enable sudo for user alarm.
 +  * Install needed packages and build needed aur packages.
 +  * Deploy PirateBoxScripts and Change some minor OS parts to let it work.
 +
 +The PirateBox service is **started by an udev rule**, which triggers after an USB wifi stick is recognized. Since 1.1.3 it does only trigger once, if two wifi cards are available. For further details, have a look into the repository or ask in the PirateBox forum.
 +