From mboxrd@z Thu Jan 1 00:00:00 1970 From: Sergio Gonzalez Monroy Subject: [PATCH v4] doc: add known issue for iommu and igb_uio Date: Mon, 15 Dec 2014 10:32:43 +0000 Message-ID: <1418639563-3599-1-git-send-email-sergio.gonzalez.monroy@intel.com> References: <1418395427-17406-1-git-send-email-sergio.gonzalez.monroy@intel.com> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable To: dev-VfR2kkLFssw@public.gmane.org Return-path: In-Reply-To: <1418395427-17406-1-git-send-email-sergio.gonzalez.monroy-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org> List-Id: patches and discussions about DPDK List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dev-bounces-VfR2kkLFssw@public.gmane.org Sender: "dev" Known issue regarding iommu/VT-d and igb_uio in Linux kernel version 3.15 to 3.17 where unbinding the device from the driver removes the 1:1 mappin= g in the iommu resulting in IOMMU/DMAR errors when the device tries to access memory. Signed-off-by: Sergio Gonzalez Monroy --- v4: Improve commit log description Add kernel error message info Improve formatting Fix patch charset encoding v3: Remove reference number Add Linux commit links v2: Fix title uppercase Add extra blank line to show proper indentation v1: Known igb_uio issue when iommu/vt-d is on doc/guides/rel_notes/known_issues.rst | 32 +++++++++++++++++++++++++++++= +++ 1 file changed, 32 insertions(+) diff --git a/doc/guides/rel_notes/known_issues.rst b/doc/guides/rel_notes= /known_issues.rst index 8ef654a..d26dcfa 100644 --- a/doc/guides/rel_notes/known_issues.rst +++ b/doc/guides/rel_notes/known_issues.rst @@ -1026,3 +1026,35 @@ Stopping the port does not down the link on Intel=C2= =AE 40G ethernet controller | Driver/Module | Poll Mode Driver (PMD) = | | | = | +--------------------------------+--------------------------------------= ------------------------------------------------+ + +Devices bound to igb_uio with VT-d enabled do not work on Linux* kernel = 3.15-3.17 +------------------------------------------------------------------------= --------- + ++--------------------------------+--------------------------------------= ------------------------------------------------+ +| Title | Devices bound to igb_uio with VT-d en= abled do not work on Linux* kernel 3.15-3.17 | ++=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D+=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D+ +| Description | | When VT-d is enabled (iommu=3Dpt in= tel_iommu=3Don), devices are 1:1 mapped. | +| | In the Linux* kernel unbinding devi= ces from drivers removes that mapping which | +| | result in IOMMU errors. = | +| | | Introduced in Linux `kernel 3.15 co= mmit `_, | +| | solved in Linux `kernel 3.18 commit= `_. | ++--------------------------------+--------------------------------------= ------------------------------------------------+ +| Implication | | Devices will not be allowed to acce= ss memory, resulting in following kernel errors:| +| | | ``dmar: DRHD: handling fault status= reg 2`` | +| | | ``dmar: DMAR:[DMA Read] Request dev= ice [02:00.0] fault addr a0c58000`` | +| | | ``DMAR:[fault reason 02] Present bi= t in context entry is clear`` | ++--------------------------------+--------------------------------------= ------------------------------------------------+ +| Resolution/ Workaround | | Use earlier or later kernel version= s, or avoid driver binding on boot by | +| | blacklisting the driver modules. = | +| | | ie. in the case of ixgbe, we can pa= ss the kernel command line option: | +| | | ``modprobe.blacklist=3Dixgbe`` = | +| | | This way we do not need to unbind t= he device to bind it to igb_uio. | ++--------------------------------+--------------------------------------= ------------------------------------------------+ +| Affected Environment/ Platform | Linux* systems with kernel versions 3= .15 to 3.17 | ++--------------------------------+--------------------------------------= ------------------------------------------------+ +| Driver/Module | igb_uio module = | ++--------------------------------+--------------------------------------= ------------------------------------------------+ --=20 1.9.3