On 20.09.16 10:45, Thomas Abraham wrote:
On Tue, Sep 20, 2016 at 12:03 PM, Alexander Graf agraf@suse.de wrote:
On 20.09.16 08:25, Thomas Abraham wrote:
On Tue, Sep 20, 2016 at 11:35 AM, Alexander Graf agraf@suse.de wrote:
Am 20.09.2016 um 07:51 schrieb Thomas Abraham ta.omasab@gmail.com:
Hi Alison,
On Mon, Sep 19, 2016 at 7:38 PM, Alexander Graf agraf@suse.de wrote:
On 09.09.16 10:48, Alison Wang wrote:
This patch is to use the the generic lowlevel_init instead of the
specific one.
Signed-off-by: Alison Wang alison.wang@nxp.com
If I had to guess, I'd think they only had their own version because the
old one required a GIC.
I apologize for the delay.
The reason for using a custom version was to avoid enabling ARMV8_MULTIENTRY config option since the Exynos7 code was ready for it.
Either way, since Samsung doesn't reply, I'm fine potentially breaking
their boards if that means that we can make progress for actively
maintained ones:
Reviewed-by: Alexander Graf agraf@suse.de
This patch without the ARMV8_MULTIENTRY and ARMV8_SWITCH_TO_EL1 config options does not switch the boot CPU from EL3 to EL1. So it would be preferable to not merge this patch until ARMV8_MULTIENTRY is enabled for Exynos7.
Why do you want to switch it to EL1 in the first place? Linux is very happy to live in EL2 - which is what we call it in by default.
Okay, there is no particular requirement to be in EL1 for Exynos7. EL2 would also be fine. But Exynos7 support in u-boot is not yet ready for enabling ARMV8_MULTIENTRY config option. Is there anything be blocked due to Exynos7 using a custom lowlevel_init function?
Yes, we're changing the semantics of armv8_switch_to_el2 and armv8_switch_to_el1:
http://lists.denx.de/pipermail/u-boot/2016-September/266217.html
which is a prerequisite for AArch32 kernel boot on AArch64 systems.
Okay.
How quickly do you think you could make Exynos7 work with MULTIENTRY?
Exynos7420 uses CPU 0 of Cluster 1 as boot CPU (master CPU). The macro 'branch_if_master' requires all affinity values to be zero for a CPU to be identified as a master CPU. And so the boot CPU is incorrectly detected as a slave CPU. I have tested with the following temporary workaround to enable ARMV8_MULTIENTRY on Exynos7420. If it looks fine, this can be merged along with Alison's patch.
That certainly works for me. Is there a particular reason why you want to do the EL1 switch? I would strongly prefer if we could just enter OSs in EL2 always.
Alex