From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 99D67C433F5 for ; Thu, 2 Dec 2021 16:59:12 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:Cc:To:Subject:Message-ID:Date:From: In-Reply-To:References:MIME-Version:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=ftW1RY+Yu+dKQFgGW4BI/1lPKkw9DN7b9dN18cNjA0I=; b=MkkpPrc9Fo4RnA v/GdRh77XFQR7/L2aah1owTWZlU1VDDBspijH3gbj2Qak5JuRt/Yw7W0TYnw8cCIXbd9oxHFdjaXP jM/FqdtiXg1Vauy3Qhe4PZbwINUwWe75SWg48weiQRhkerSIBo1n309UpuGkASoRp09cMZ8d+RFFR 9PYaLclbyfFkVKHGu4WJUm89fhjDgR67kUsI8gAimTCrt669n3Yg2SnKG/Q3Wy4JdKHKbcPjpceBz JeWa0TljIJZW1U/zikJ+y1pUWfmqZjJM/hD1bvsnkj3RZwzSTnbTWxkR/oVin8LYARdRDzlw5s2i4 jFe2wyd2CiUGoKPRU9Ig==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1mspQI-00D66b-Lb; Thu, 02 Dec 2021 16:59:06 +0000 Received: from dfw.source.kernel.org ([139.178.84.217]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1mspQF-00D660-7E for linux-riscv@lists.infradead.org; Thu, 02 Dec 2021 16:59:04 +0000 Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 250BA6273B for ; Thu, 2 Dec 2021 16:59:02 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 039BCC56747 for ; Thu, 2 Dec 2021 16:59:01 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1638464341; bh=/zy9qvCwC1lAjmsE078OPisiQGtPoPxqKNVBrrN6XXs=; h=References:In-Reply-To:From:Date:Subject:To:Cc:From; b=WwAaiL/gR25W+IonZj9sYrecCbW4eHPTUR/0TVqYC3o4oAeTIbKjMYZBh2rFHby6V UgTpYy9BdgyTbs9FtdxGqqVVehgYXjnI0ibFsbXjDkM2yxXjW2q+T4zjMwx4RD5c7r z9Zx+Pk595HOJDOUgQRb3lxR/tqzW5TGfTBLFWLnJr52p2ObAmdrTvo52jj3oMHtEf 6uPJsTjLdnyz+f7Zdjd69OtT91z3uiqmvseY1nOeoUnhivGdIY//I+iw4L2W0yIIB5 ELmZyt0le9koRWaEvCr+XZzOP6f4JnPJxkxYHIKnHI1p6teSPpFPNlxvQwlLM9NCUw ON/4vDVSzKtww== Received: by mail-ot1-f46.google.com with SMTP id w6-20020a9d77c6000000b0055e804fa524so487008otl.3 for ; Thu, 02 Dec 2021 08:59:00 -0800 (PST) X-Gm-Message-State: AOAM532GHaX7wJYRPO1Iz/uhrEffAaiieKw6kA9Gq/60hkpcEzI1TrGH l90ZxM1vv9LjbhLLB9TSlfTCuASnds8nmu0Rm8o= X-Google-Smtp-Source: ABdhPJzNYU3KcsPOfgK75CP8sfk4bKUtw8ZnnubGz6bBm4PdFkty416497FIfvKAiFUiOq2rb3ZbT/+XCrOUd+h9Pe4= X-Received: by 2002:a05:6830:1514:: with SMTP id k20mr11964593otp.147.1638464340156; Thu, 02 Dec 2021 08:59:00 -0800 (PST) MIME-Version: 1.0 References: <20211202150515.GA97518@sunil-ThinkPad-T490> <89d42547-ec36-5f84-88d1-fd65d891488c@canonical.com> In-Reply-To: <89d42547-ec36-5f84-88d1-fd65d891488c@canonical.com> From: Ard Biesheuvel Date: Thu, 2 Dec 2021 17:58:49 +0100 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: Question regarding "boot-hartid" DT node To: Heinrich Schuchardt Cc: Atish Patra , Abner Chang , Jessica Clarke , Anup Patel , Palmer Dabbelt , sunil.vl@gmail.com, linux-riscv , Sunil V L X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20211202_085903_362102_9DB432CD X-CRM114-Status: GOOD ( 26.34 ) X-BeenThere: linux-riscv@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-riscv" Errors-To: linux-riscv-bounces+linux-riscv=archiver.kernel.org@lists.infradead.org On Thu, 2 Dec 2021 at 17:53, Heinrich Schuchardt wrote: > > On 12/2/21 17:20, Ard Biesheuvel wrote: > > On Thu, 2 Dec 2021 at 16:05, Sunil V L wrote: > >> > >> Hi All, > >> I am starting this thread to discuss about the "boot-hartid" DT node > >> that is being used in RISC-V Linux EFI stub. > >> > >> As you know, the boot Hart ID is passed in a0 register to the kernel > >> and hence there is actually no need to pass it via DT. However, since > >> EFI stub follows EFI application calling conventions, it needs to > >> know the boot Hart ID so that it can pass it to the proper kernel via > >> a0. For this issue, the solution was to add "/chosen/boot-hartid" in > >> DT. Both EDK2 and u-boot append this node in DT. > >> > > > > I think this was a mistake tbh > > > >> But above approach causes issue for ACPI since ACPI initialization > >> happens late in the proper kernel. Same is true even if we pass this > >> information via SMBIOS. > >> > > > > It would be better to define a RISCV specific EFI protocol that the > > stub can call to discover the boot-hartid value. That wat, it can pass > > it directly, without having to rely on firmware tables. > > As discovering the current process' hartid is not a UEFI specific task > SBI would be a better fit. > I disagree. The OS<->loader firmware interface is UEFI not SBI. So if the EFI stub needs to ask the firmware which boot-hartid it should pass in A0, it should use a EFI protocol and nothing else. Whether or not the loader/firmware *implements* this EFI protocol by calling into SBI is a different matter (and likely the best choice). But that does not mean the EFI stub should make SBI calls directly. _______________________________________________ linux-riscv mailing list linux-riscv@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-riscv