f44f8b07b0
OpenWrt uses a lot of (b)ash scripts for initial setup. This isn't the
best solution as they almost never consider syncing files / data. Still
this is what we have and we need to try living with it.
Without proper syncing OpenWrt can easily get into an inconsistent state
on power cut. It's because:
1. Actual (flash) inode and data writes are not synchronized
2. Data writeback can take up to 30 seconds (dirty_expire_centisecs)
3. ubifs adds extra 5 seconds (dirty_writeback_centisecs) "delay"
Some possible cases (examples) for new files:
1. Power cut during 5 seconds after write() can result in all data loss
2. Power cut happening between 5 and 35 seconds after write() can result
in empty file (inode flushed after 5 seconds, data flush queued)
Above affects e.g. uci-defaults. After executing some migration script
it may get deleted (whited out) without generated data getting actually
written. Power cut will result in missing data and deleted file.
There are three ways of dealing with that:
1. Rewriting all user-space init to proper C with syncs
2. Trying bash hacks (like creating tmp files & moving them)
3. Adding sync and hoping for no power cut during critical section
This change introduces the last solution that is the simplest. It
reduces time during which things may go wrong from ~35 seconds to
probably less than a second. Of course it applies only to IO operations
performed before /etc/init.d/boot . It's probably the stage when the
most new files get created.
All later changes are usually done using smarter C apps (e.g. busybox or
uci) that creates tmp files and uses rename() that is expected to be
atomic.
Signed-off-by: Rafał Miłecki <rafal@milecki.pl>
Acked-by: Hauke Mehrtens <hauke@hauke-m.de>
Acked-by: Sergey Ryazanov <ryazanov.s.a@gmail.com>
(cherry picked from commit
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| .github | ||
| config | ||
| include | ||
| LICENSES | ||
| package | ||
| scripts | ||
| target | ||
| toolchain | ||
| tools | ||
| .gitattributes | ||
| .gitignore | ||
| BSDmakefile | ||
| Config.in | ||
| COPYING | ||
| feeds.conf.default | ||
| Makefile | ||
| README.md | ||
| rules.mk | ||
OpenWrt Project is a Linux operating system targeting embedded devices. Instead of trying to create a single, static firmware, OpenWrt provides a fully writable filesystem with package management. This frees you from the application selection and configuration provided by the vendor and allows you to customize the device through the use of packages to suit any application. For developers, OpenWrt is the framework to build an application without having to build a complete firmware around it; for users this means the ability for full customization, to use the device in ways never envisioned.
Sunshine!
Development
To build your own firmware you need a GNU/Linux, BSD or MacOSX system (case sensitive filesystem required). Cygwin is unsupported because of the lack of a case sensitive file system.
Requirements
You need the following tools to compile OpenWrt, the package names vary between distributions. A complete list with distribution specific packages is found in the Build System Setup documentation.
gcc binutils bzip2 flex python3 perl make find grep diff unzip gawk getopt
subversion libz-dev libc-dev rsync which
Quickstart
-
Run
./scripts/feeds update -ato obtain all the latest package definitions defined in feeds.conf / feeds.conf.default -
Run
./scripts/feeds install -ato install symlinks for all obtained packages into package/feeds/ -
Run
make menuconfigto select your preferred configuration for the toolchain, target system & firmware packages. -
Run
maketo build your firmware. This will download all sources, build the cross-compile toolchain and then cross-compile the GNU/Linux kernel & all chosen applications for your target system.
Related Repositories
The main repository uses multiple sub-repositories to manage packages of
different categories. All packages are installed via the OpenWrt package
manager called opkg. If you're looking to develop the web interface or port
packages to OpenWrt, please find the fitting repository below.
-
LuCI Web Interface: Modern and modular interface to control the device via a web browser.
-
OpenWrt Packages: Community repository of ported packages.
-
OpenWrt Routing: Packages specifically focused on (mesh) routing.
Support Information
For a list of supported devices see the OpenWrt Hardware Database
Documentation
Support Community
- Forum: For usage, projects, discussions and hardware advise.
- Support Chat: Channel
#openwrton oftc.net.
Developer Community
- Bug Reports: Report bugs in OpenWrt
- Dev Mailing List: Send patches
- Dev Chat: Channel
#openwrt-develon oftc.net.
License
OpenWrt is licensed under GPL-2.0