Hi Marc, On Wed, Mar 11, 2015 at 11:47 PM, Marc Zyngier <marc.zyngier@xxxxxxx> wrote: > On 11/03/15 17:57, Feng Kan wrote: >> On Wed, Mar 11, 2015 at 10:31 AM, Marc Zyngier <marc.zyngier@xxxxxxx> wrote: >>> On 11/03/15 17:19, Feng Kan wrote: >>>> On Wed, Mar 11, 2015 at 7:53 AM, Marc Zyngier <marc.zyngier@xxxxxxx> wrote: >>>>> On 27/01/15 07:03, Pranavkumar Sawargaonkar wrote: >>>>>> In APM X-Gene, GIC register space is 64K aligned while the sizes mentioned >>>>>> in the dt are 4K aligned. This breaks KVM when kernel is built with 64K page >>>>>> size due to size alignment checking in vgic driver for VCPU Control and >>>>>> VCPU register. >>>>>> >>>>>> This patch corrects the sizes to be inline with the hardware spec. >>>>> >>>>> This patch may be correct, but it is useless. The firmware on my APM >>>>> system (some version of u-boot) repaints the DT at boot time, negating >>>>> the effect of this patch. >>>> We have updated u-boot to reflect this change. I can supply you with a updated >>>> image if you wish. >>> >>> That would be useful, thanks. >>> >>> But more importantly, why bother upstreaming your DT into the kernel >>> tree if your firmware is going to overwrite whatever we provide? >> We did tried to submit a version upstream but was rejected. >> >>> >>> Either the firmware let the user provide its own DT (and doesn't touch >>> it other than to change the CPU enable method, insert a /memreserve/ or >>> similar things), or the firmware always provide its own DT, and doesn't >>> let the user provide its own. Corrupting the user DT is a disaster, as >>> we just found. >> Yes, the intent of the change is listed in the link below. It is not a >> justification by any means, >> just the effects of things appearing in layers. >> http://lists.infradead.org/pipermail/linux-arm-kernel/2014-September/288574.html > > Yeah. This is as wrong as it can possibly be. Oh well... Yes there is an issue with u-boot patching the dt for end user who wants his DT to be used, for this we can (in fact we should) provide an option in u-boot (may be setting some environment variable) which will make sure end user's DT does not get modified (apart from standard things like patching mac-addresses) by u-boot. Another point I want to reopen here is the how to handle 64K GIC page size pointed out in this thread, what would be the best way to tackle this (adding a new DT string or any other way) ? Thanks, Pranav > > Thanks, > > M. > -- > Jazz is not dead. It just smells funny... -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
