From mboxrd@z Thu Jan 1 00:00:00 1970 From: Siarhei Siamashka Date: Fri, 25 Jul 2014 03:21:03 +0300 Subject: [U-Boot] [PATCH 2/2] sunxi: Set the AUXCR L2EN bit for sun4i/sun5i in FEL boot mode In-Reply-To: <1405976391.4100.37.camel@hastur.hellion.org.uk> References: <1405703385-14580-1-git-send-email-siarhei.siamashka@gmail.com> <1405703385-14580-3-git-send-email-siarhei.siamashka@gmail.com> <53C96BD4.1020307@myspectrum.nl> <1405973237.4100.34.camel@hastur.hellion.org.uk> <53CD7A82.7010705@myspectrum.nl> <1405976391.4100.37.camel@hastur.hellion.org.uk> Message-ID: <20140725032103.089c88e8@i7> List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: u-boot@lists.denx.de On Mon, 21 Jul 2014 21:59:51 +0100 Ian Campbell 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 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. -- Best regards, Siarhei Siamashka