On Wed, 2011-12-21 at 16:42 -0800, Tim Bird wrote: > On 12/21/2011 04:18 PM, john stultz wrote: > > On Wed, 2011-12-21 at 15:19 -0800, Greg KH wrote: > >> On Wed, Dec 21, 2011 at 02:59:15PM -0800, Tim Bird wrote: > >>> Hi all, > >>> > >>> I'm looking for feedback on the Android logger code, to see what > >>> it would take to make this code acceptable for inclusion in > >>> the mainline kernel. > >>> > >>> Information about the features of Android logging system > >>> can be found at: http://elinux.org/Android_Logging_System > >>> > >>> This system creates a new system-wide logging service, in > >>> the kernel, for user-space message. It is more comparable > >>> to syslog than to the kernel log buffer, as it holds only > >>> user-space messages. It is optimized for write > >>> performance, since most of the time the log is written to > >>> and never read. It creates multiple log channels, to prevent > >>> an abundance of log messages in one channel from overwriting > >>> messages in another channel. The log channels have sizes > >>> fixed at kernel compile-time. > >>> > >>> Log messages are stored in very simple in-kernel buffers, that > >>> overflow old messages upon wrapping. A fixed set of attributes > >>> (pid, tid, timestamp and message), is kept for each message. > >>> By convention, Android puts a message priority and context tag > >>> into each message. > >>> > >>> In Android, this system uses a fixed set of device nodes with > >>> well-known names: /dev/log/main, /dev/log/events, /dev/log/radio > >>> and /dev/log/system. > >>> > >>> Operations on the log are done via a character device, using > >>> standard file operations and some ioctls. > >>> > >>> The code for this is below (I've moved it from linux-next > >>> drivers/staging/android for my own testing). > >>> > >>> Please let me know what issues you see with this code. > >> > >> That all describes the current code, but you haven't described what's > >> wrong with the existing syslog interface that requires this new driver > >> to be written. And why can't the existing interface be fixed to address > >> these (potential) shortcomings? > >> > >>> One specific question I have is where is the most appropriate > >>> place for this code to live, in the kernel source tree? > >>> Other embedded systems might want to use this system (it > >>> is simpler than syslog, and superior in some ways), so I don't > >>> think it should remain in an android-specific directory. > >> > >> What way is it superior? Again, why not extend syslog? Why not "fix" > >> syslog if this really is a superior thing? How does this tie into Kay > >> and Lennard's proposal for work in this area? > > > > There is also some overlap functionality wise with pstore as well, as I > > believe the logger is used as a known location in memory where messages > > can be fetched from after a kernel panic or crash. > > I don't know if that's true or not. I think you may be thinking > of Android's RAM console feature. If there's a way to save > application messages over a reboot using the logger buffers, I'm > unfamiliar with it. I may very well be confusing things. I had thought apanic pulled the logger data, but maybe I'm wrong. thanks -john -- To unsubscribe from this list: send the line "unsubscribe linux-embedded" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
