From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andrew Cooper Subject: Re: Buggy IOMMU support in Coreboot on Chromebook Pixel 2 i7-5600U Date: Sat, 15 Aug 2015 06:58:14 +0100 Message-ID: <55CED4F6.1050204@citrix.com> References: <55CDA9B5.6030406@citrix.com> <142b6f50010c565ba7a87cf93993ef7b@riseup.net> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii"; Format="flowed" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <142b6f50010c565ba7a87cf93993ef7b@riseup.net> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xen.org Errors-To: xen-devel-bounces@lists.xen.org To: fowlslegs@riseup.net, Xen-devel@lists.xen.org List-Id: xen-devel@lists.xenproject.org On 15/08/15 06:14, fowlslegs@riseup.net wrote: > On 2015-08-14 01:41, Andrew Cooper wrote: >> On 14/08/15 08:13, fowlslegs@riseup.net wrote: >>> On the VT-d troubleshooting page, I was informed to shoot you all a >>> message if Xen had to deactivate my VT-d due to errors in my BIOS >>> (in this case Coreboot). I am running John Lewis' Coreboot ROM for >>> the Chromebook Pixel 2 (samus) w/ the i7-5600U processor and Xen >>> 4.4.2 on Qubes. I downloaded and cracked open (for lack of better >>> words) John Lewis's Coreboot image (which is a modified version of >>> the one in the Google repos) and found that src/arch/x86/acpi.c had >>> the same section added by the http://review.coreboot.org/#/c/1654/ >>> commit written by Patrick Georgi a few years back that is supposed >>> to provide ACPI DMAR tables. The problem might just be the code is >>> out of date for modern processors or maybe it has just not been >>> tested against many CPUs. >>> >>> It does appear that there has been changes to this acpi.c file in >>> the Coreboot master branch, which makes me wonder if building >>> against that would fix my problems. Realistically though, I have >>> barely any experience or knowledge with Coreboot hacking and I'm >>> assuming there is a web of dependencies that I couldn't figure out >>> without possibly months of research, trial, and error. >>> >>> Anyway, just wanted to send in this report as maybe you don't get >>> too many involving Coreboot and maybe you might find it interesting >>> or in the minute chance you might be able to help me out. Anyway, >>> here's the output of `xl dmesg`: >> >> Please reboot and use "iommu=verbose,debug" on the Xen command line, >> which will offer more information. >> >> ~Andrew >> > > I was already passing iommu=verbose, but not debug as well. Here is > the new log Not the one you posted. Line 4 prints the full command line as passed to Xen. Anyhow, ... > > Xen 4.4.2-6.fc20 > (XEN) Xen version 4.4.2 (user@) (gcc (GCC) 4.8.3 20140911 (Red Hat > 4.8.3-7)) debug=n Thu Jul 23 20:12:15 UTC 2015 > (XEN) Latest ChangeSet: > (XEN) Bootloader: GRUB 2.00 > (XEN) Command line: placeholder console=none dom0_mem=min:1024M > iommu=verbose,debug > (XEN) Video information: > (XEN) VGA is text mode 80x25, font 8x16 > (XEN) Disc information: > (XEN) Found 2 MBR signatures > (XEN) Found 2 EDD information structures > (XEN) Xen-e820 RAM map: > (XEN) 0000000000000000 - 000000000009fc00 (usable) > (XEN) 000000000009fc00 - 00000000000a0000 (reserved) > (XEN) 00000000000f0000 - 0000000000100000 (reserved) > (XEN) 0000000000100000 - 000000007ce27000 (usable) > (XEN) 000000007ce27000 - 0000000080000000 (reserved) > (XEN) 00000000f0000000 - 00000000f4000000 (reserved) > (XEN) 00000000fed10000 - 00000000fed1a000 (reserved) > (XEN) 00000000fed40000 - 00000000fed45000 (reserved) > (XEN) 00000000fed80000 - 00000000fed85000 (reserved) > (XEN) 0000000100000000 - 000000047f000000 (usable) > (XEN) ACPI: RSDP 000F2760, 0024 (r2 CORE ) > (XEN) ACPI: XSDT 7CF440E0, 004C (r1 CORE COREBOOT 0 > CORE 0) > (XEN) ACPI: FACP 7CF48970, 00F4 (r5 CORE COREBOOT 0 > CORE 1) > (XEN) ACPI: DSDT 7CF44250, 4720 (r2 COREv4 COREBOOT 20110725 INTL > 20130117) > (XEN) ACPI: FACS 7CF44210, 0040 > (XEN) ACPI: HPET 7CF48A70, 0038 (r1 CORE COREBOOT 0 > CORE 0) > (XEN) ACPI: APIC 7CF48AB0, 006C (r1 CORE COREBOOT 0 > CORE 0) > (XEN) ACPI: MCFG 7CF48B20, 003C (r1 CORE COREBOOT 0 > CORE 0) > (XEN) ACPI: SSDT 7CF49BC0, 0FF8 (r2 CORE COREBOOT 2A > CORE 2A) > (XEN) System RAM: 16317MB (16709400kB) ... there is no DMAR table, which means that coreboot has not told Xen that an IOMMU exists on the system. ~Andrew