On Mon, 2014-06-02 at 20:48 +0200, Alain Kalker wrote: > Reduce the lernel log level to KERN_NOTICE for messages related > to a missing caching mode page. > > Reasons why I think this change is justified: > - The condition is not an error; the existing workaround of assuming > a write through cache doesn't limit functionality in any way. That's not actually correct. The condition may be an error. We have some USB attached storage devices with writeback caches which don't supply caching information. Treating a writeback device as writethrough is a potential error because you may lose data as a result of it. The error is that we've made an assumption which may damage your data. The problem for us is that we can't tell if the assumption is going to be fatal or not ... the message is harmless for older USB devices. > - It doesn't warrant a warning either: as it is most likely > a hardware limitation, there is little that an ordinary user can do > about it besides replacing the affected hardware. > Making it a warning would still break quiet boot (kernel commandline > parameter 'quiet'), and may still trip log monitoring software > unneccessarily, either on every boot or whenever an affected > external device is plugged in. > - It should be a notice, for it is a normal but significant condition, > as it may impact write performance. This would bring it on par with > the log messages in the same function. But this message may serve a purpose: If you see it and you find you do have a USB device with a writeback cache, you can set the boot system to correct the cache type assumption and we'll send the correcting synchronize cache commands. It certainly helps bug triagers identify issues which may require adding a particular device to the list that need to be treated as writeback. James -- To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
