arm/173617

[Brian J. McGovern]

On Mon, 2013-03-04 at 15:52 -0700, Ian Lepore wrote:
> On Mon, 2013-03-04 at 16:55 -0500, Brian J. McGovern wrote:
> > I have been chasing down a disk write problem my OpenRD. In my research, I
> > ran across arm/173617, which discusses file corruption while downloading ports
> > via fetch, which is how I first noticed the issue. However, contrary to the PR,
> > the issues does not appear to be in the network interface, but rather on the
> > writing of the file to disk. The problem appears global - I've tested SATA,
> > USB (umass), and SD/MMC interfaces. I've also had problems with NFS mounts in 
> > the past, but have not verified that the issues are the same.
> > 
> > I have not chased down a particular size, but "small" writes (e.g. a config
> > file, .c file, etc.) appear to work correctly at all times. "Large" writes
> > (I usually see it on files a MB or larger, but this may be a function of 
> > opportunity) will typically see some number of bytes set to zero. To reproduce
> > the problem, I wrote a short application that writes sequentially incrementing
> > 64-bit integers out to disk. (e.g. 0, 1, 2, 3...), and one that reads them 
> > back.
> > 
> > The result matrix clearly showed the problem is on the write side - writing
> > files on other systems and reading them back on the OpenRD works fine. Writing
> > them on the OpenRD causes read back failures, both on the OpenRD _and_ other
> > hosts. I have also found that setting the file handle O_SYNC (or mounting
> > the filesystem in sync mode) eliminates the problem.
> > 
> > Has anyone seen/fixed this problem? I'd hate to waste much more time with it
> > if its a known problem, or there is a closed PR I haven't found yet.
> > 
> 
> You didn't say what version of freebsd you're working with.  I saw a
> problem like that a while back on my similar DreamPlug; the symptom was
> random chunks of corruption that were always 32 bytes of wrong data
> each.  I think the fix for that was to disable cache write-allocate on
> sheeva chipsets; that fix came into -current along with all the armv6
> changes, but I have it as a separate patch too.
> 
> -- Ian
> 
> 
> 
Sorry. The tests were specifically with 9.1-RELEASE. 

Most of the time, I've seen 64 bits of corruption, and all zeros, rather
than "wrong data", although early on I did see some other values occur,
although I thought it may have been a 32 vs. 64 bit issues with ints
until I went to uint64_t. 

Is -current working well enough to build a stable platform? Can you
email me the patch privately, and I'll see if I can get it working on 9?

  -Brian