On Tue, Aug 26, 2014 at 11:14:14AM +0100, Will Deacon wrote: > On Mon, Aug 18, 2014 at 10:58:09AM +0100, Kever Yang wrote: > > From: Huang Tao <huang...@rock-chips.com> > > > > On Cortex-A12 (r0p0..r0p1-00lac0-rc11), when a CPU executes a sequence of > > two conditional store instructions with opposite condition code and > > updating the same register, the system might enter a deadlock if the > > second conditional instruction is an UNPREDICTABLE STR or STM > > instruction. This workaround setting bit[12] of the Feature Register > > prevents the erratum. This bit disables an optimisation applied to a > > sequence of 2 instructions that use opposing condition codes. > > > > Signed-off-by: Huang Tao <huang...@rock-chips.com> > > Signed-off-by: Kever Yang <kever.y...@rock-chips.com> > > --- > > The Rk3288 I have advertises itself as an r0p1 Cortex-A12 CPU, so isn't > affected by this issue. Until we have an SoC supported in mainline that > requires this workaround, I don't think we should merge it. > > Also, please consider setting these bits in your firmware if possible. > The feature register isn't writable from the non-secure side, so if you > want to use virtualisation you'll need to do this differently.
I think we're at the point where we start insisting that workarounds which are simple enable/disable feature bit operations (in other words, which can be handled by updating a control register in the firmware or boot loader) must be done that way, and we are not going to add such workarounds to the kernel anymore. -- FTTC broadband for 0.8mile line: currently at 9.5Mbps down 400kbps up according to speedtest.net. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/