The email was moderated, re-sending on behalf of Andrei.

From: Andrei Stefanescu <andrei.stefanescu@nxp.com>
Sent: 13 May 2025 12:35
To: tf-a@lists.trustedfirmware.org <tf-a@lists.trustedfirmware.org>
Cc: Ghennadi Procopciuc <ghennadi.procopciuc@nxp.com>; Ciprian Marian Costea <ciprianmarian.costea@nxp.com>; Alexandru-Catalin Ionita <alexandru-catalin.ionita@nxp.com>
Subject: Question about memory mapping attributes for MT_DEVICE

Hi,

I noticed that the memory mapping attributes for MT_DEVICE memory are defined to: nGnRE [1]. Why was nGnRE selected instead of nGnRnE?

Platforms which have USE_COHERENT_MEM set to 1 will map the coherent memory area as MT_DEVICE. This area is helpful for cases where a backery lock is shared between cores which have MMU enabled and cores which don’t (whose access is equivalent to nGnRnE). This would generate an access attributes mismatch for the coherent memory area.

Would it be ok to send a patch which changes the ATTR_DEVICE to nGnRnE?

Best regards,
Andrei Stefanescu

[1] - https://git.trustedfirmware.org/plugins/gitiles/TF-A/trusted-firmware-a.git/+/refs/heads/master/include/lib/xlat_tables/xlat_tables_defs.h#152