From owner-freebsd-stable@freebsd.org Sun Sep 4 15:50:42 2016 Return-Path: Delivered-To: freebsd-stable@mailman.ysv.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) by mailman.ysv.freebsd.org (Postfix) with ESMTP id A4956A9D50D for ; Sun, 4 Sep 2016 15:50:42 +0000 (UTC) (envelope-from avg@FreeBSD.org) Received: from mailman.ysv.freebsd.org (mailman.ysv.freebsd.org [IPv6:2001:1900:2254:206a::50:5]) by mx1.freebsd.org (Postfix) with ESMTP id 8FEC6E87 for ; Sun, 4 Sep 2016 15:50:42 +0000 (UTC) (envelope-from avg@FreeBSD.org) Received: by mailman.ysv.freebsd.org (Postfix) id 8B9F9A9D50B; Sun, 4 Sep 2016 15:50:42 +0000 (UTC) Delivered-To: stable@mailman.ysv.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) by mailman.ysv.freebsd.org (Postfix) with ESMTP id 8B355A9D50A for ; Sun, 4 Sep 2016 15:50:42 +0000 (UTC) (envelope-from avg@FreeBSD.org) Received: from citapm.icyb.net.ua (citapm.icyb.net.ua [212.40.38.140]) by mx1.freebsd.org (Postfix) with ESMTP id DDCF4E86 for ; Sun, 4 Sep 2016 15:50:41 +0000 (UTC) (envelope-from avg@FreeBSD.org) Received: from porto.starpoint.kiev.ua (porto-e.starpoint.kiev.ua [212.40.38.100]) by citapm.icyb.net.ua (8.8.8p3/ICyb-2.3exp) with ESMTP id SAA17556; Sun, 04 Sep 2016 18:50:40 +0300 (EEST) (envelope-from avg@FreeBSD.org) Received: from localhost ([127.0.0.1]) by porto.starpoint.kiev.ua with esmtp (Exim 4.34 (FreeBSD)) id 1bgZgt-000J13-SM; Sun, 04 Sep 2016 18:50:39 +0300 Subject: Re: X2APIC support To: Konstantin Belousov References: <20151212130615.GE70867@zxy.spb.ru> <20151212133513.GL82577@kib.kiev.ua> <20160901112724.GX88122@zxy.spb.ru> <20160901114500.GJ83214@kib.kiev.ua> <20160901121300.GZ88122@zxy.spb.ru> <4ba05c00-f737-f562-553d-a7fa59145768@FreeBSD.org> <20160904151415.GE83214@kib.kiev.ua> Cc: Slawa Olhovchenkov , stable@FreeBSD.org From: Andriy Gapon Message-ID: Date: Sun, 4 Sep 2016 18:49:43 +0300 User-Agent: Mozilla/5.0 (X11; FreeBSD amd64; rv:45.0) Gecko/20100101 Thunderbird/45.2.0 MIME-Version: 1.0 In-Reply-To: <20160904151415.GE83214@kib.kiev.ua> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit X-BeenThere: freebsd-stable@freebsd.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: Production branch of FreeBSD source code List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sun, 04 Sep 2016 15:50:42 -0000 On 04/09/2016 18:14, Konstantin Belousov wrote: > On Sun, Sep 04, 2016 at 11:19:16AM +0300, Andriy Gapon wrote: >> Kostik, I see one strange thing which is common to both successful and >> unsuccessful configurations. All "SMP: Added CPU..." lines have "AP" in them. >> It seems like the platform does not tell explicitly tell which CPU is the BSP, >> see cpu_add() function. This can break quite a few assumption. And I am not >> even sure how the successful scenario works. >> Ah... I see that there is a backup code in cpu_mp_start() where boot_cpu_id is >> set based on the current CPU's Local APIC ID. I suspect then that this >> information is incorrect in the failing case. >> > Well, there is no easy way to read the LAPIC Id of BSP before LAPICs > are initialized. BIOS might reprogram LAPIC Ids, so reading from > CPUID[1].EBX[31:24] might return incorrect data. Even more incorrect > it might be in the x2APIC state, since 8 bits are not enough for 32bit > x2APIC Id. Hmm, I am not sure how what you are saying here is relevant to the problem. I believe that cpu_mp_start() is executed (on the BSP) after the BSP's LAPIC is initialized. So, the code should just work. My theory was that the BSP's LAPIC ID was incorrectly programmed by BIOS (firmware). -- Andriy Gapon