On Fri, 2014-07-25 at 03:21 +0300, Siarhei Siamashka wrote: > On Mon, 21 Jul 2014 21:59:51 +0100 > Ian Campbell <[email protected]> wrote: > > > On Mon, 2014-07-21 at 22:39 +0200, Jeroen Hofstee wrote: > > > Hello Ian, > > > > > > On 21-07-14 22:07, Ian Campbell wrote: > > > > On Fri, 2014-07-18 at 20:47 +0200, Jeroen Hofstee wrote: > > > >> Hello Siarhei, > > > >> > > > >> On 18-07-14 19:09, Siarhei Siamashka wrote: > > > >>> This is needed to have feature parity with the normal boot mode, > > > >>> where the L2EN bit in the CP15 Auxiliary Control Register is set > > > >>> by the BROM code right from the start. > > > >>> > > > >>> If this is not done, the Linux system ends up booted with the L2 cache > > > >>> disabled. > > > >>> > > > >> I don't know a single about the sunxi, but shouldn't linux > > > >> be patched instead. The commit message seems to indicate > > > >> it is not an u-boot issue. > > > > The ACTLR may not be writeable from NS mode so it has to be setup in the > > > > bootloader before dropping to NS mode. > > > mmm, I guess there is something wrong with the boot sequence > > > if the kernel itself can't access raw hw. > > > > Do you know what ARM Secure and Non-Secure worlds are? > > > > The kernel expects to be launched in NS mode and simply cannot access > > this register. This is a feature not a bug. > > Just curious. Is there a modern consensus about how this all is > supposed to be done nowadays?
The kernel's Booting.txt strongly encourages you to enter in HYP mode if it is available, which implies NS mode. This a basic requirement to use virtualisation (Xen or KVM etc). I believe that the general consensus is to run in NS mode on newer platforms by default. FWIW on v8 arm64 Linux documentation requires NS mode. > The last time I read anything about this subject was the following > longish and already old discussion thread (which has probably > already lost relevance): > > http://lists.linaro.org/pipermail/boot-architecture/2011-August/000060.html > > Since the Allwinner BROM does not forcefully drop us to the non-secure > mode, we have the absolute freedom of choice and may implement any > policy. We do, and we should implement PSCI and NS boot for kernels. Ian. _______________________________________________ U-Boot mailing list [email protected] http://lists.denx.de/mailman/listinfo/u-boot
