> -----Original Message----- > From: Wood Scott-B07421 > Sent: Tuesday, March 05, 2013 7:46 AM > To: Stuart Yoder > Cc: Jia Hongtao-B38951; linuxppc-dev@lists.ozlabs.org; Kumar Gala > Subject: Re: [PATCH V4] powerpc/85xx: Add machine check handler to fix > PCIe erratum on mpc85xx > > On 03/04/2013 10:16:10 AM, Stuart Yoder wrote: > > On Mon, Mar 4, 2013 at 2:40 AM, Jia Hongtao <b38...@freescale.com> > > wrote: > > > A PCIe erratum of mpc85xx may causes a core hang when a link of PCIe > > > goes down. when the link goes down, Non-posted transactions issued > > > via the ATMU requiring completion result in an instruction stall. > > > At the same time a machine-check exception is generated to the core > > > to allow further processing by the handler. We implements the > > handler > > > which skips the instruction caused the stall. > > > > Can you explain at a high level how just skipping an instruction > > solves > > anything? If you just skip a load/store and continue like nothing is > > wrong, isn't your system possibly in a really bad state. > > If the instruction was a load, we probably at least want to fill the > destination register with 0xffffffff or similar.
You discuss this with Liu Shuo about a year ago. here is the log: " On 02/01/2012 02:18 AM, shuo....@freescale.com wrote: > v3 : Skip the instruction only. Don't access the user space memory in > mechine check. It may be the least bad option for now, but be aware that there's a small chance that this will cause a leak of sensitive information (such as a piece of a crypto key that happened to be sitting in the register to be loaded into). -Scott " -Hongtao. > > > And if the core is already hung, due to the PCI link going down, isn't > > it too late? How does skipping help? > > Maybe the machine check unhangs the core? > > Is there an erratum number for this? > > -Scott _______________________________________________ Linuxppc-dev mailing list Linuxppc-dev@lists.ozlabs.org https://lists.ozlabs.org/listinfo/linuxppc-dev
