On Wed, 2011-12-21 at 16:49 -0800, john stultz wrote: > 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. Looks like I am wrong. Apologies. Thanks for pointing my error out. -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
