From mboxrd@z Thu Jan 1 00:00:00 1970 Delivery-date: Thu, 12 Jun 2025 00:24:23 +0200 Received: from metis.whiteo.stw.pengutronix.de ([2a0a:edc0:2:b01:1d::104]) by lore.white.stw.pengutronix.de with esmtps (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.96) (envelope-from ) id 1uPTrr-006Iq2-1O for lore@lore.pengutronix.de; Thu, 12 Jun 2025 00:24:23 +0200 Received: from bombadil.infradead.org ([2607:7c80:54:3::133]) by metis.whiteo.stw.pengutronix.de with esmtps (TLS1.3:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1uPTrq-0004K1-TP for lore@pengutronix.de; Thu, 12 Jun 2025 00:24:23 +0200 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:Content-Transfer-Encoding: Content-Type:Subject:Cc:To:From:MIME-Version:Date:Message-ID:Reply-To: Content-ID:Content-Description:Resent-Date:Resent-From:Resent-Sender: Resent-To:Resent-Cc:Resent-Message-ID:In-Reply-To:References:List-Owner; bh=tHVWvq7CBG7b+tMhdCEldZUAVuAGhnVbaVfpV2IQllY=; b=qwwMP9KrKDYuOHtkUGAy3S+XKZ D+HMaBgJOK+VVWXLf2iNp43s8eaKgEI3Naw/hKiY0X5bFFypjcYVyzkLPMNmK0rSv2L4lfF1NyxHJ Jq7+htB9xyyDWg8fhbsckXxapqA29+eo+DJQVN0oVM2+i2Won1uvqxVmJgzffqZiFeTiyGlXAiV0w 9ISyMTUNe7ArHcDmMJgR36CvCNFGsRClf+p7EPTzjvpYSUOL/IdSIu+v17Doas0ui2KyFfmvnAJJa jq9xcIknq+DGqn8fjzZBYtP9kLeWVuSsDnuS1IzraxjdlH4q4GXlhKhbGrJbLAxL7r1k2xKogXTj8 8kpFm8Dw==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98.2 #2 (Red Hat Linux)) id 1uPTrh-0000000BT5q-3udo; Wed, 11 Jun 2025 22:24:13 +0000 Received: from metis.whiteo.stw.pengutronix.de ([2a0a:edc0:2:b01:1d::104]) by bombadil.infradead.org with esmtps (Exim 4.98.2 #2 (Red Hat Linux)) id 1uPPtR-0000000AqRb-472j for barebox@lists.infradead.org; Wed, 11 Jun 2025 18:09:47 +0000 Received: from ptz.office.stw.pengutronix.de ([2a0a:edc0:0:900:1d::77] helo=[127.0.0.1]) by metis.whiteo.stw.pengutronix.de with esmtp (Exim 4.92) (envelope-from ) id 1uPPtN-00012L-8z; Wed, 11 Jun 2025 20:09:41 +0200 Message-ID: <89ad64f2-fbda-48a3-9a27-5eaff5be9292@pengutronix.de> Date: Wed, 11 Jun 2025 20:09:40 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Content-Language: en-US, de-DE, de-BE From: Ahmad Fatoum To: manish.pandey2@arm.com Cc: op-tee@lists.trustedfirmware.org, BAREBOX , rouven.czerwinski@linaro.org, Michael Tretter , "kernel@pengutronix.de" Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20250611_110946_022560_6AC34F45 X-CRM114-Status: GOOD ( 11.93 ) X-BeenThere: barebox@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "barebox" X-SA-Exim-Connect-IP: 2607:7c80:54:3::133 X-SA-Exim-Mail-From: barebox-bounces+lore=pengutronix.de@lists.infradead.org X-Spam-Checker-Version: SpamAssassin 3.4.2 (2018-09-13) on metis.whiteo.stw.pengutronix.de X-Spam-Level: X-Spam-Status: No, score=-5.2 required=4.0 tests=AWL,BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,RCVD_IN_DNSWL_MED,SPF_HELO_NONE,SPF_NONE autolearn=unavailable autolearn_force=no version=3.4.2 Subject: Firmware Handoff for DT Overlay created by OP-TEE? X-SA-Exim-Version: 4.2.1 (built Wed, 08 May 2019 21:11:16 +0000) X-SA-Exim-Scanned: Yes (on metis.whiteo.stw.pengutronix.de) Hello Manish, In your recent talk[1] at LinaroConnect about the Firmware Handoff specification, you were asking about what other use cases it could address for OP-TEE. We ran into a possible use case that we would like to share: BL2 can pass a DT to OP-TEE, which it would use to discover memory and to fix up with memory reservations covering the memory it carves out for itself. OP-TEE also supports passing along the reservations as a device tree overlay. AFAICS, there is no way currently to have both: A DT for OP-TEE to probe hardware from and a way to pass the normal world a device tree overlay in return. I think this could be neatly addressed with Firmware Handoff and would be a motivation for us to implement support in barebox BL2/BL33 to take advantage of this. The current way is suboptimal as we would prefer the DT passed to OP-TEE to be read-only. This avoids either having to copy it or to pad it sufficiently in anticipation of it growing with the addition of the new nodes. [1]: https://www.youtube.com/watch?v=RxU798h8aiE Cheers, Ahmad -- Pengutronix e.K. | | Steuerwalder Str. 21 | http://www.pengutronix.de/ | 31137 Hildesheim, Germany | Phone: +49-5121-206917-0 | Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 |