FreeBSD P4 USB project - precompiled kernels available for download

[Ben Kelly]

On Dec 29, 2007, at 3:38 AM, Hans Petter Selasky wrote:
> On Saturday 29 December 2007, Ben Kelly wrote:
>> It didn't look like there had been any USB changes in there
>> recently.  Has the USB development moved completely to p4?
>
> Just for the time being. I will update my SVN repo soon so that you  
> can get
> the source code and compile for yourself.

Thanks!

>> I would like to try the new stack, but I am guessing I will need to
>> patch it for usb/95173 in order to use my umass device.
>
> Usually it is best if patches go into FreeBSD current first,  
> because else I
> will have to keep track of the patches I take in. Regarding your  
> patch, it
> looks OK, except it would be nice if the patch could be modified so  
> that it
> automatically detects these quirks. Because adding quirks is a bad  
> solution
> in the long run.

I agree that quirks are not the best solution.  Unfortunately,  
though, I don't think it will be possible to detect the problem and  
dynamically disable sync'ing.  At least this particular USB-to-disk  
controller seems to lockup when the sync command is issued.  It  
requires a power cycle to recover the device.

It did occur to me, however, that perhaps it would make sense to  
disable sync'ing for all umass devices by default and then add a  
quirk to enable the feature on devices where its known to be  
beneficial.  This is based on the (perhaps dubious) theory that most  
umass devices probably do not do a lot of caching because of the risk  
of being disconnected at any time.  I didn't pursue this option,  
though, since I thought it would be more controversial and harder to  
get applied to the tree.

> Maybe you have another USB mass storage device you can test ?

I think I can probably find one.  Eventually I would like to test my  
hard drive enclosure, though, since I use it the most often  
currently.  I probably won't be able to run the tests until after the  
new year.

Thanks again.

- Ben