From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) by mx.groups.io with SMTP id smtpd.web08.9161.1637660728025046317 for ; Tue, 23 Nov 2021 01:45:28 -0800 Authentication-Results: mx.groups.io; dkim=pass header.i=@redhat.com header.s=mimecast20190719 header.b=U5MqUDXF; spf=pass (domain: redhat.com, ip: 170.10.129.124, mailfrom: kraxel@redhat.com) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1637660727; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=KUqns8NLREF2f3L/YARb5fE3KESZQ2sYLOg7loSBeZ8=; b=U5MqUDXF9AzXWVPdL9rjmor4etg19aWXWHGmvShC46wvf4hMvEAkmgANUZsxfO0pU7EwoB VHnuw6EroDJZHwZFtaPnspSlbW6Bxi7NyIKz7CitGSVCrA7WXTYh7Rfx1mct6ZXHdJ1Pdz 7g6pvPlERXPL9WSSB+jc7V21Fnp3PUg= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-511-tDT34bKiPGCU2U_Cy014zg-1; Tue, 23 Nov 2021 04:45:21 -0500 X-MC-Unique: tDT34bKiPGCU2U_Cy014zg-1 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.phx2.redhat.com [10.5.11.15]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 1169687D546; Tue, 23 Nov 2021 09:45:20 +0000 (UTC) Received: from sirius.home.kraxel.org (unknown [10.39.192.79]) by smtp.corp.redhat.com (Postfix) with ESMTPS id B0FCF5F4E0; Tue, 23 Nov 2021 09:45:19 +0000 (UTC) Received: by sirius.home.kraxel.org (Postfix, from userid 1000) id 000201800936; Tue, 23 Nov 2021 10:45:17 +0100 (CET) Date: Tue, 23 Nov 2021 10:45:17 +0100 From: "Gerd Hoffmann" To: "Xu, Min M" Cc: "Ni, Ray" , "devel@edk2.groups.io" , Rebecca Cran , Peter Grehan , Tom Lendacky , Anthony Perard , "Yao, Jiewen" , "Dong, Eric" Subject: Re: [PATCH V3 3/3] OvmfPkg: Move LocalApicTimerDxe to UefiCpuPkg Message-ID: <20211123094517.sja253rzqxaizh36@sirius.home.kraxel.org> References: <69c2eeac1fb327acc92626886477755b6b12e044.1636350203.git.min.m.xu@intel.com> MIME-Version: 1.0 In-Reply-To: X-Scanned-By: MIMEDefang 2.79 on 10.5.11.15 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=kraxel@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Hi, > > 2. Can SourceLevelDebug (rely on Local APIC timer) work if this driver is > > chosen as DXE timer driver? > After checking the code and running the PoC (enable SourceLevelDebug and LocalApicTimerDxe), I find this driver doesn't work anymore. > Actually it asserts in https://github.com/mxu9/edk2/blob/ovmf_lapic_timer.v3/UefiCpuPkg/LocalApicTimerDxe/LocalApicTimerDxe.c#L334 Hmm, I guess this makes LocalApicTimerDxe alot less useful on physical hardware. So keep it in OvmdPkg? For virtual machines there are other debugging options, using qemu's builtin gdb server for example, so SourceLevelDebug not being available isn't a big issue IMHO. > For TDVF we assume SourceLevelDebug is not supported. So LocalApicTimerDxe is still working for TDVF. > > For other VM guests in OvmfPkg, can we assume SourceLevelDebug is NOT supported after LocalApicTimer is used (the older timer is 8254)? > @ Gerd Hoffmann (OvmfPkg) Fine with me. > @ Anthony Perard , Julien Grall (Xen) Xen already uses the apic timer today, so that shouldn't be a problem either ;) take care, Gerd