From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from us-smtp-delivery-1.mimecast.com (us-smtp-delivery-1.mimecast.com [205.139.110.61]) by mx.groups.io with SMTP id smtpd.web12.25004.1594153328639937759 for ; Tue, 07 Jul 2020 13:22:09 -0700 Authentication-Results: mx.groups.io; dkim=pass header.i=@redhat.com header.s=mimecast20190719 header.b=UjdkhNXw; spf=pass (domain: redhat.com, ip: 205.139.110.61, mailfrom: lersek@redhat.com) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1594153327; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=k/xYmy3ramYvwdPRCelDlf4tQx/sXnyzAG6VCi/qjnI=; b=UjdkhNXwsiVIX0AZH/yqAIshTylEsNpKT2eDljI+SJ+xvReo2UxxYPt2GuoBKxhtcpaxhP /QzifBA51FHcal5Y1NZiQM1NSlrWCEc2D3MmM9faKaKXHIRlvjBcStZ81i/gULFD/gMvMD 692tJOLflljjCQF4PR0XR1uycoigGew= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-254-s8z-c0BOOsuppUAiGIe_zw-1; Tue, 07 Jul 2020 16:21:54 -0400 X-MC-Unique: s8z-c0BOOsuppUAiGIe_zw-1 Received: from smtp.corp.redhat.com (int-mx08.intmail.prod.int.phx2.redhat.com [10.5.11.23]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id C824A18A8220; Tue, 7 Jul 2020 20:21:53 +0000 (UTC) Received: from lacos-laptop-7.usersys.redhat.com (ovpn-114-90.ams2.redhat.com [10.36.114.90]) by smtp.corp.redhat.com (Postfix) with ESMTP id 162A619D7D; Tue, 7 Jul 2020 20:21:52 +0000 (UTC) Subject: Re: [edk2-devel] 2nd OVMF question about why InitRootBridge does not set ResourceAssigned? From: "Laszlo Ersek" To: devel@edk2.groups.io, afish@apple.com References: <19FB2158-0F1A-4EDF-86FC-04095AE1066E@apple.com> Message-ID: Date: Tue, 7 Jul 2020 22:21:52 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Firefox/52.0 Thunderbird/52.9.1 MIME-Version: 1.0 In-Reply-To: X-Scanned-By: MIMEDefang 2.84 on 10.5.11.23 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=lersek@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Language: en-US Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit On 07/07/20 21:59, Laszlo Ersek wrote: > (Side note: where I say "synthetic", that does not mean "easy to change" > at all. Coming up with good 32-bit and 64-bit MMIO apertures for the > PciHostBridgeLib instance was an arduous task. Among other things, this > originates from the very quirky placement of the 32-bit address ranges > on i440fx and q35 that are usable for PCI MMIO. QEMU doesn't dictate the > apertures for the root bridges, but if you allocate an MMIO BAR from an > inappropriate address range, you're doomed.) A key commit regarding the above is 49edde15230a ("OvmfPkg/PlatformPei: set 32-bit UC area at PciBase / PciExBarBase (pc/q35)", 2019-06-03). It was very difficult to find a 32-bit PCI MMIO aperture, facing any random guest RAM size, such that we could mark the aperture in PlatformPei as UC with no more than the 8 variable MTRRs that QEMU provides. https://bugzilla.tianocore.org/show_bug.cgi?id=1814 https://bugzilla.tianocore.org/show_bug.cgi?id=1859 Thanks Laszlo