Date: Fri, 25 Oct 2013 15:03:10 -0600 From: Ian Lepore <ian@FreeBSD.org> To: Steven Lee <ssl.qlt@gmail.com> Cc: freebsd-arm@FreeBSD.org Subject: Re: Dreamplug stable/10 usb - sd file transfer corruption error - cache related? Message-ID: <1382734990.1170.132.camel@revolution.hippie.lan> In-Reply-To: <CALD1=P=gWosQsTTYt=hpkasP8y1rH3oH6y0n-y=APP_X0S%2BYFQ@mail.gmail.com> References: <CALD1=P=gWosQsTTYt=hpkasP8y1rH3oH6y0n-y=APP_X0S%2BYFQ@mail.gmail.com>
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On Fri, 2013-10-25 at 13:37 -0700, Steven Lee wrote: > Hello, > > In the process of upgrading my Dreamplug from the stable/9 branch to the > stable/10 branch, I have run into a fairly > significant file corruption problem. The steps that create this problem > are as follows: > > 1. Cross-compile the kernel and buildworld from the stable/10 branch on a > separate host. > 2. Install the kernel and installworld on a usb stick drive > 3. Boot the Dreamplug from the usb drive > > There are no problems that show up to this point, the Dreamplug boots with > no errors. > > 4. Copy the kernel from the usb drive to the internal sd card > 5. Copy the root filesystem from the usb drive to the internal sd card > using (dump | restore) > > It is at step 5 that the error manifests itself, as I found that > approximately 20 shell scripts in the /etc/rc.d directory > had been randomly corrupted with strings of null characters (in groups of > 32). I assume that the rest of the file system > was compromised in a similar fashion. The bug is repeatable, however the > corruption is somewhat random, so > each time different files are corrupted in different places. > > When I followed the exact same steps from the stable/9 branch, the problem > did not occur, so there is clearly some > type of regression error between the 9 and 10 branches. > > After searching through the arm mailing list, I attempted to work around > the problem by: > - mounting the file systems with -o noclusterr -o noclusterrw > - mounting the file systems with -o sync > - as per comments on bug arm/158950, attempted to modify the pmap.c > functions to change the cache from > write-back mode to write-through mode > > but all of these attempts were ineffective. > > Given that I am relatively new to FreeBSD, I was hoping to get any insights > as to any next steps that might make > sense in terms of either working around the problem, narrowing down the > bug, or any obvious rookie mistakes I > am making before I give up and revert back to the 9 branch. > > Thanks for your help! > > Regards, On my dreamplug (model 1001) both the internal and external sd cards are actually usb devices (they show up as /dev/da0 and da1, not mmcsd0/1). I'm not sure if that's true on all models or not. Are you using the stock kernel config (DREAMPLUG-1001)? If not, have you got "option USB_HOST_ALIGN=32" in your kernel config? Corruption in 32 byte chunks is almost always partial cacheline flush problems, but I haven't seen that happen on dreamplug for a long time (and when I did see it, it was with a sata drive). -- Ian
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