* David VomLehn <dvomlehn@xxxxxxxxx> wrote: > Parallelization to improve boot times has been successful enough > that race conditions now exist between the init_post() open of > /dev/console and initialization of the console device. When this > occurs, opening /dev/console fails and any applications inherited > from init have no standard in/out/error devices. This is expected > behavior if no console device is available, but quite unfortunate > in the case where the console is just a bit slow waking up. > > Some buses, such as USB, offer no guarantees about how long it > takes to discover devices, so there is no reliable way to > distinguish between a missing console and a slow one. The > pragmatic approach taken in this patch is to wait for a while to > see if a console shows up, and just go on if it doesn't. The > default delay is 1000 msec (1 second). This value is conjured out > of thing air; any suggestions for a value that more closely > approximates the effective delays from the olden days before USB > consoles starting failing are more than welcome. hm, this really seems like a bad hack and a workaround to me and as such it is not really an acceptable solution. The proper approach would be to use one of the async_synchronize*() facilities in kernel/async.c to properly order the opening of the console with device init. Certain subsystems like storage (SCSI, libata, mount code and modules) has already been extended to this scheme. So i think the right approach, if you want to speed up bootup, would be to extend the same concepts to console discovery, init and open methods. Ingo -- 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
