On Tue, 2016-08-23 at 13:34 +0200, Christophe Leroy wrote: > > Le 23/08/2016 à 11:20, Alessio Igor Bogani a écrit : > > > > Hi Christophe, > > > > Sorry for delay in reply I was on vacation. > > > > On 6 August 2016 at 11:29, christophe leroy <christophe.le...@c-s.fr> > > wrote: > > > > > > Alessio, > > > > > > > > > Le 05/08/2016 à 09:51, Christophe Leroy a écrit : > > > > > > > > > > > > > > > > > > > > Le 19/07/2016 à 23:52, Scott Wood a écrit : > > > > > > > > > > > > > > > On Tue, 2016-07-19 at 12:00 +0200, Alessio Igor Bogani wrote: > > > > > > > > > > > > > > > > > > Hi all, > > > > > > > > > > > > I have got two boards MVME5100 (MPC7410 cpu) and MVME7100 > > > > > > (MPC8641D > > > > > > cpu) for which I use the same cross-compiler (ppc7400). > > > > > > > > > > > > I tested these against kernel HEAD to found that these don't boot > > > > > > anymore (PID 1 crash). > > > > > > > > > > > > Bisecting results in first offending commit: > > > > > > 7aef4136566b0539a1a98391181e188905e33401 > > > > > > > > > > > > Removing it from HEAD make boards boot properly again. > > > > > > > > > > > > A third system based on P2010 isn't affected at all. > > > > > > > > > > > > Is it a regression or I have made something wrong? > > > > > > > > > > I booted both my next branch, and Linus's master on MPC8641HPCN and > > > > > didn't see > > > > > this -- though possibly your RFS is doing something > > > > > different. Maybe > > > > > that's > > > > > the difference with P2010 as well. > > > > > > > > > > Is there any way you can debug the cause of the crash? Or send me a > > > > > minimal > > > > > RFS that demonstrates the problem (ideally with debug symbols on the > > > > > userspace > > > > > binaries)? > > > > > > > > > I got from Alessio the below information: > > > > > > > > systemd[1]: Caught <BUS>, core dump failed (child 137, code=killed, > > > > status=7/BUS). > > > > systemd[1]: Freezing execution. > > > > > > > > > > > > What can generate SIGBUS ? > > > > And shouldn't we also get some KERN_ERR trace, something like > > > > "unhandled > > > > signal 7 at ....." ? > > > > > > > As far as I can see, SIGBUS is mainly generated from alignment > > > exception. > > > According to 7410 Reference Manual, alignment exception can happen in > > > the > > > following cases: > > > * An operand of a dcbz instruction is on a page that is write-through or > > > cache-inhibited for a virtual mode access. > > > * An attempt to execute a dcbz instruction occurs when the cache is > > > disabled > > > or locked. > > > > > > Could try with below patch to check if the dcbz insn is causing the > > > SIGBUS ? > > Unfortunately that patch doesn't solve the problem. > > > > Is there a chance that cache behavior could settled by board firmware > > (PPCBug on the MPC7410 board and MotLoad on the MPC8641D one)? > > In that case what do you suggest me to looking for? > If the removal of dcbz doesn't solve the issue, I don't think it is a > cache related issue. > As far as I understood, your init gets a SIGBUS signal, right ? Then we > must identify the reason for that sigbus.
My guess would be errors demand-loading a page via NFS. One approach might be to hack up the code so that both versions of csum_partial_copy_generic() are present, and call both each time. If the results differ or the copied bytes are wrong, then spit out a dump of the details. -Scott
