[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCH] xen: arm: setup sane EL1 state while building domain 0.
On 03/18/2014 05:41 PM, Ian Campbell wrote: > On Tue, 2014-03-18 at 11:22 +0800, Fu Wei wrote: >> On 03/17/2014 11:31 PM, Ian Campbell wrote: >>> The address translation functions used while building dom0 rely on certain >>> EL1 >>> state being configured. In particular they are subject to the behaviour of >>> SCTLR_EL1.M (stage 1 MMU enabled). >>> >>> The Xen (and Linux) boot protocol require that the kernel be entered with >>> the >>> MMU disabled but they don't say anything explicitly about exception levels >>> other than the one which is active when entering the kernels. Arguably the >>> protocol could be said to apply to all exception levels but in any case we >>> should cope with this and setup the EL1 state as necessary. >>> >>> Fu Wei discovered this when booting Xen from grub.efi over UEFI, it's not >>> clear whether grub or UEFI is responsible for leaving stage 1 MMU enabled. >>> >>> Reported-by: Fu Wei <fu.wei@xxxxxxxxxx> >>> Signed-off-by: Ian Campbell <ian.campbell@xxxxxxxxxx> >>> Cc: Fu Wei <fu.wei@xxxxxxxxxx> >>> --- >>> Fu Wei, can I add your Tested-by here? >> >> Yes, Thanks! >> I have tested this with my GRUB binary, it works fine. > > Great. Thanks. It looks like we might rework the approach, if so I'll CC > you on that as well (or Julien will). > > Are you also going to change grub to leave EL1 in a known good state? I don't think it's the work of grub to modify EL1 register. if the booting.txt(xen or linux) doesn't mention about EL1, I think the kernel(xen or linux) should take care of these EL1 registers. And at the time, xen has booted up, it can modify EL1 registers. Do you agree? :-) > > Ian. > > -- Best regards, Fu Wei LAVA Engineer From Red Hat LAVA Team Linaro.org | Open source software for ARM SoCs Ph: +86 186 2020 4684 (mobile) IRC: fuwei Skype: tekkamanninja Room 1512, Regus One Corporate Avenue,Level 15, One Corporate Avenue,222 Hubin Road,Huangpu District, Shanghai,China 200021 _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx http://lists.xen.org/xen-devel
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