Re: applesmc oops in 3.10/3.11

[Henrik Rydberg]

On Wed, Oct 02, 2013 at 09:47:18AM -0700, Guenter Roeck wrote:
> On Wed, Oct 02, 2013 at 06:34:18PM +0200, Henrik Rydberg wrote:
> > > >>One thing I have seen in all logs is the earlier "send_byte fail" message, so
> > > >>I think that is a pre-requisite.
> > > >
> > > >Not necessarily - it could be that the patch actually fixes the root
> > > >cause. One possible scenario is that on recent SMCs, some of the
> > > >commands produce more data than we actually read. This would
> > > >eventually lead to both data corruption and overflow somwhere in the
> > > >SMC internals.  If the original SMC error is interpreted as a read
> > > >buffer overflow, then that problem should be fixed with this patch.
> > > >
> > > 
> > > Good point.
> > > 
> > > But shouldn't we at least get the "flushed %d bytes" warning message in this case ?
> > 
> > The explanation I have there is that the (newer) SMC needs the
> > application to read the 'no more bytes' or it will get confused. It
> > makes sense, if the number of bytes to read is no longer specified.
> > 
> You mean that just reading from APPLESMC_CMD_PORT would solve the problem ?
> That might make sense.

It also points at the possibility of a smaller patch to test, but I
have not had the time to check this very deeply myself:

Thanks,
Henrik