Sorry for a delay. I didn't have a bandwidth for doing it. I asked my teammate Marcin Salnik for testing the fix https://review.trustedfirmware.org/c/TF-A/trusted-firmware-a/+/3493 on our Veloce emulator.

Now, I can confirm that this fix works. ACC BL31 booted.

From: Varun Wadekar vwadekar@nvidia.com Sent: Monday, June 01, 2020 8:57 PM To: Witkowski, Andrzej andrzej.witkowski@intel.com Cc: Lessnau, Adam adam.lessnau@intel.com; tf-a@lists.trustedfirmware.org Subject: RE: Unhandled Exception at EL3 in BL31 for Neoverse N1 with direct connect of DSU

Hi,

I believe the fix for this issue is part of https://review.trustedfirmware.org/c/TF-A/trusted-firmware-a/+/3493. Can you please try that change?

-Varun

From: TF-A <tf-a-bounces@lists.trustedfirmware.orgmailto:tf-a-bounces@lists.trustedfirmware.org> On Behalf Of Witkowski, Andrzej via TF-A Sent: Monday, June 1, 2020 7:08 AM To: tf-a@lists.trustedfirmware.orgmailto:tf-a@lists.trustedfirmware.org Cc: Witkowski, Andrzej <andrzej.witkowski@intel.commailto:andrzej.witkowski@intel.com>; Lessnau, Adam <adam.lessnau@intel.commailto:adam.lessnau@intel.com> Subject: [TF-A] Unhandled Exception at EL3 in BL31 for Neoverse N1 with direct connect of DSU

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Hi,

I work on project which uses ARM CPU Neoverse N1 with direct connect of DSU. I noticed the following error "Unhandled Exception at EL3" in BL31 bootloader after switching from ATF 2.1 to 2.2. The root cause is that after invoking neoverse_n1_errata-report function in lib/cpus/aarch64/neoverse_n1.S file and reaching the line 525, the function check_errata_dsu_934 in lib/cpus/aarch64/dsu_helpers.S file is always invoked regardless of whether ERRATA_DSU_936184 is set to 0 or to 1. In our case, ERRATA_DSU_936184 := 0.

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[cid:image002.png@01D64A40.BBEF1AA0]

Neoverse N1 with direct connect version of DSU doesn't contain SCU/L3 cache and CLUSTERCFR_EL1 register. The error "Unhandled Exception at EL3" appears in BL31 bootloader during attempt to read the CLUSTERCFR_EL1 register which doesn't exist in our RTL HW.

Andrzej Witkowskie Intel Technology Poland

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