From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail02.groups.io (mail02.groups.io [66.175.222.108]) by spool.mail.gandi.net (Postfix) with ESMTPS id E32D57803CC for ; Thu, 22 Feb 2024 01:49:52 +0000 (UTC) DKIM-Signature: a=rsa-sha256; bh=BbyEn1x9jDAG5TFDHg4MQsAaOvCTtFbRlY0/wMRB89Y=; c=relaxed/simple; d=groups.io; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From:In-Reply-To:Precedence:List-Subscribe:List-Help:Sender:List-Id:Mailing-List:Delivered-To:Reply-To:List-Unsubscribe-Post:List-Unsubscribe:Content-Language:Content-Type:Content-Transfer-Encoding; s=20140610; t=1708566591; v=1; b=JWHVqKYEErGNcrAwtbD7aR6tDUAXwMy1RvgvrB4E9IJvYfBOMPufUrPP7w2WOqZV+7x0WWTg g8i0at2VscNNoYXyfao5LKm7g9rUopUJ+1ER2pCSU+KfdiMY97Q8pdooGnzCl91Si5gTtL5uF+q AczAMAR7jCMocVfDT413vpL4= X-Received: by 127.0.0.2 with SMTP id YRWkYY7687511xPz5QPQA0tn; Wed, 21 Feb 2024 17:49:51 -0800 X-Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by mx.groups.io with SMTP id smtpd.web10.3846.1708566590930697383 for ; Wed, 21 Feb 2024 17:49:51 -0800 X-Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-294-Q95cijoSPy-K_A71tTcN-A-1; Wed, 21 Feb 2024 20:49:48 -0500 X-MC-Unique: Q95cijoSPy-K_A71tTcN-A-1 X-Received: from smtp.corp.redhat.com (int-mx10.intmail.prod.int.rdu2.redhat.com [10.11.54.10]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id EC5F68352A1; Thu, 22 Feb 2024 01:49:47 +0000 (UTC) X-Received: from [10.39.192.46] (unknown [10.39.192.46]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 4EDCE492BD7; Thu, 22 Feb 2024 01:49:46 +0000 (UTC) Message-ID: <18d3de31-c7d9-f1d6-77f7-e147679349b1@redhat.com> Date: Thu, 22 Feb 2024 02:49:45 +0100 MIME-Version: 1.0 Subject: Re: [edk2-devel] [PATCH v2 5/5] UefiCpuPkg/MpInitLib: Add support for multiple HOBs to SaveCpuMpData() To: devel@edk2.groups.io, kraxel@redhat.com, ray.ni@intel.com Cc: Oliver Steffen , "Kumar, Rahul R" References: <20240220174939.1288689-1-kraxel@redhat.com> <20240220174939.1288689-6-kraxel@redhat.com> From: "Laszlo Ersek" In-Reply-To: X-Scanned-By: MIMEDefang 3.4.1 on 10.11.54.10 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Precedence: Bulk List-Subscribe: List-Help: Sender: devel@edk2.groups.io List-Id: Mailing-List: list devel@edk2.groups.io; contact devel+owner@edk2.groups.io Reply-To: devel@edk2.groups.io,lersek@redhat.com List-Unsubscribe-Post: List-Unsubscribe=One-Click List-Unsubscribe: X-Gm-Message-State: FveGcbnYESM52EshDxJ1RAfPx7686176AA= Content-Language: en-US Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-GND-Status: LEGIT Authentication-Results: spool.mail.gandi.net; dkim=pass header.d=groups.io header.s=20140610 header.b=JWHVqKYE; dmarc=fail reason="SPF not aligned (relaxed), DKIM not aligned (relaxed)" header.from=redhat.com (policy=none); spf=pass (spool.mail.gandi.net: domain of bounce@groups.io designates 66.175.222.108 as permitted sender) smtp.mailfrom=bounce@groups.io (commenting once more, to explain the actual reason:) On 2/21/24 11:24, Gerd Hoffmann wrote: > On Wed, Feb 21, 2024 at 03:48:25AM +0000, Ni, Ray wrote: >>> >>> + MaxCpusPerHob = (MAX_UINT16 - sizeof (EFI_HOB_GUID_TYPE) - sizeof >>> (MP_HAND_OFF)) / sizeof (PROCESSOR_HAND_OFF); >> >> Above formula assumes the maximum HOB length could be 0xFFFF. > > Which is IMHO correct. It is not correct: > >> But actually the maximum HOB length could be only 0xFFF8 because >> PeiCore::PeiCreateHob() contains following logic: >> >> if (0x10000 - Length <= 0x7) { >> return EFI_INVALID_PARAMETER; >> } > > That Length is the *data* size, the HOB header is not included. > > The "- sizeof (EFI_HOB_GUID_TYPE)" in the formula above accounts the > space needed for HOB header and GUID. Yes, but the problem is not that we need the extra space for EFI_HOB_GUID_TYPE (24 bytes) -- we need the extra space for padding / alignment. This is what the PI spec says (v1.8, section "III-4.5.2 HOB Construction Rules"): HOB construction must obey the following rules: [...] 4. All HOBs must be multiples of 8 bytes in length. This requirement meets the alignment restrictions of the Itanium® processor family. [...] And if your total *desired* HOB length exceeds 0xFFF8 (i.e., it falls in [0xFFF9..0xFFFF]), then the required upwards rounding produces 0x1_0000. But that rounded-up value cannot be expressed in "EFI_HOB_GENERIC_HEADER.HobLength" -- a UINT16 field. In short, you've got Itanium to thank for this. :) Laszlo -=-=-=-=-=-=-=-=-=-=-=- Groups.io Links: You receive all messages sent to this group. View/Reply Online (#115768): https://edk2.groups.io/g/devel/message/115768 Mute This Topic: https://groups.io/mt/104472313/7686176 Group Owner: devel+owner@edk2.groups.io Unsubscribe: https://edk2.groups.io/g/devel/unsub [rebecca@openfw.io] -=-=-=-=-=-=-=-=-=-=-=-