On Thu, Dec 22, 2011 at 12:20:26PM +1100, NeilBrown wrote: > On Wed, 21 Dec 2011 16:36:21 -0800 Tim Bird <tim.b...@am.sony.com> wrote: > > > On 12/21/2011 03:19 PM, Greg KH wrote: > > > 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? > > > > Here are some ways that this code is superior to syslog: > > It is certainly nice and simple. It really looks more like a filesystem than > a char device though... though they aren't really files so much as lossy > pipes. I don't think that's a problem though, lots of things in filesystems > don't behave exactly like files. > > If you created a 'logbuf' filesystem that used libfs to provide a single > directory in which privileged processes could create files then you wouldn't > need the kernel to "know" the allowed logs: radio, events, main, system. > The size could be set by ftruncate() (by privileged used again) rather than > being hardcoded. > > You would defined 'read' and 'write' much like you currently do to create a > list of > datagrams in a circular buffer and replace the ioctls by more standard > interfaces: > > LOGGER_GET_LOG_BUG_SIZE would use 'stat' and the st_blocks field > LOGGER_GET_LOG_LEN would use 'stat' and the st_size field > LOGGER_GET_NEXT_ENTRY_LEN could use the FIONREAD ioctl > LOGGER_FLUSH_LOG could use ftruncate > > The result would be much the same amount of code, but an interface which has > fewer details hard-coded and is generally more versatile and accessible.
But, almost all of this is already in the syslog system call today, right? So why create a new user api for something we have? greg k-h -- To unsubscribe from this list: send the line "unsubscribe linux-embedded" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
