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From: Jerin Jacob Kollanukkaran <jerinj@marvell.com>
To: "Burakov, Anatoly" <anatoly.burakov@intel.com>,
	Thomas Monjalon <thomas@monjalon.net>
Cc: "Stojaczyk, Dariusz" <dariusz.stojaczyk@intel.com>,
	David Marchand <david.marchand@redhat.com>,
	"dev@dpdk.org" <dev@dpdk.org>
Subject: Re: [dpdk-dev] [EXT] Re: [PATCH v4 0/4] Fixes on IOVA mode selection
Date: Tue, 23 Jul 2019 14:36:26 +0000
Message-ID: <BYAPR18MB2424D34D0C04791D915B11BDC8C70@BYAPR18MB2424.namprd18.prod.outlook.com> (raw)
In-Reply-To: <3e82b693-6680-ee0d-b5cb-4f2e881e6ba3@intel.com>

> -----Original Message-----
> From: Burakov, Anatoly <anatoly.burakov@intel.com>
> Sent: Tuesday, July 23, 2019 8:00 PM
> To: Thomas Monjalon <thomas@monjalon.net>
> Cc: Jerin Jacob Kollanukkaran <jerinj@marvell.com>; Stojaczyk, Dariusz
> <dariusz.stojaczyk@intel.com>; David Marchand
> <david.marchand@redhat.com>; dev@dpdk.org
> Subject: [EXT] Re: [dpdk-dev] [PATCH v4 0/4] Fixes on IOVA mode selection
> On 23-Jul-19 2:56 PM, Burakov, Anatoly wrote:
> > On 23-Jul-19 11:25 AM, Thomas Monjalon wrote:
> >> 23/07/2019 11:57, Burakov, Anatoly:
> >>> A machine without an IOMMU shouldn't have picked IOVA as VA in the
> >>> first place. Perhaps this is something we could fix? I'm not sure
> >>> how to detected that condition though, i don't think there's a
> >>> mechanism to know that for sure. Some kernels create a "iommu" sysfs
> >>> directories, but i'm not too sure if they're 1) there for older
> >>> kernels we support, and
> >>> 2) always there.
> >> [..]
> >>> On my machine, "/sys/devices/virtual/iommu" exists when IOMMU is
> >>> enabled, but doesn't exist if it isn't ("/sys/class/iommu" exists in
> >>> both cases, but is empty when IOMMU is disabled). Perhaps we could
> >>> go off that?
> >>
> >> Yes, good idea.
> >> We need to check how these sysfs entries are managed, and how old
> >> they are by looking at Linux code history.
> >>
> >
> > Quick (and by no means thorough) Google reveals that IOMMU driver's
> > sysfs-related code dates back as far as kernel version 3.17:
> >
> > https://elixir.bootlin.com/linux/v3.17.8/source/drivers/iommu/iommu-sy
> > sfs.c
> >
> > I'm not a kernel code expert, but the code *looks* like it's creating
> > an IOMMU-related entry in sysfs. So, i take it we can be reasonably
> > sure of these entries' presence at least since v3.17 onwards? Do we
> > support kernels which don't have this code?
> >
> 
> After a short chat with Ferruh, i think we have even better way to determine
> whether IOMMU is enabled - the /sys/kernel/iommu filesystem.
> Those are created whenever it is possible for VFIO to run, even if VFIO driver
> itself is not loaded. These have been there since kernel 3.6, so our minimum
> requirements are met with this approach, i believe.

I can see /sys/kernel/iommu_groups/ on IOMMU systems not  /sys/kernel/iommu

> --
> Thanks,
> Anatoly

  reply index

Thread overview: 57+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-07-10 21:48 [dpdk-dev] [PATCH 0/2] " David Marchand
2019-07-10 21:48 ` [dpdk-dev] [PATCH 1/2] Revert "bus/pci: add Mellanox kernel driver type" David Marchand
2019-07-16 10:37   ` [dpdk-dev] [EXT] " Jerin Jacob Kollanukkaran
2019-07-10 21:48 ` [dpdk-dev] [PATCH 2/2] eal: fix IOVA mode selection as VA for pci drivers David Marchand
2019-07-11 14:40   ` Thomas Monjalon
2019-07-12  8:05     ` Jerin Jacob Kollanukkaran
2019-07-12 11:03   ` Burakov, Anatoly
2019-07-12 12:43     ` Thomas Monjalon
2019-07-12 12:58       ` Burakov, Anatoly
2019-07-12 13:19         ` Bruce Richardson
2019-07-15 14:26       ` Jerin Jacob Kollanukkaran
2019-07-15 15:03         ` Thomas Monjalon
2019-07-15 15:35           ` Jerin Jacob Kollanukkaran
2019-07-15 16:06             ` Thomas Monjalon
2019-07-15 16:27               ` Jerin Jacob Kollanukkaran
2019-07-16 13:46 ` [dpdk-dev] [PATCH v2 0/4] Fixes on IOVA mode selection jerinj
2019-07-16 13:46   ` [dpdk-dev] [PATCH v2 1/4] Revert "bus/pci: add Mellanox kernel driver type" jerinj
2019-07-16 13:46   ` [dpdk-dev] [PATCH v2 2/4] eal: fix IOVA mode selection as VA for pci drivers jerinj
2019-07-16 14:26     ` Burakov, Anatoly
2019-07-16 15:07       ` Jerin Jacob Kollanukkaran
2019-07-16 13:46   ` [dpdk-dev] [PATCH v2 3/4] eal: change RTE_PCI_DRV_IOVA_AS_VA flag name jerinj
2019-07-16 13:46   ` [dpdk-dev] [PATCH v2 4/4] eal: select IOVA mode as VA for default case jerinj
2019-07-16 14:33     ` Burakov, Anatoly
2019-07-17  8:33       ` [dpdk-dev] [EXT] " Jerin Jacob Kollanukkaran
2019-07-17 12:38         ` Burakov, Anatoly
2019-07-17 14:04           ` Jerin Jacob Kollanukkaran
2019-07-18  6:45   ` [dpdk-dev] [PATCH v3 0/4] Fixes on IOVA mode selection jerinj
2019-07-18  6:45     ` [dpdk-dev] [PATCH v3 1/4] Revert "bus/pci: add Mellanox kernel driver type" jerinj
2019-07-18  6:45     ` [dpdk-dev] [PATCH v3 2/4] eal: fix IOVA mode selection as VA for pci drivers jerinj
2019-07-18  6:45     ` [dpdk-dev] [PATCH v3 3/4] eal: change RTE_PCI_DRV_IOVA_AS_VA flag name jerinj
2019-07-18  6:45     ` [dpdk-dev] [PATCH v3 4/4] eal: select IOVA mode as VA for default case jerinj
2019-07-22 11:28     ` [dpdk-dev] [PATCH v3 0/4] Fixes on IOVA mode selection David Marchand
2019-07-22 12:56 ` [dpdk-dev] [PATCH v4 " David Marchand
2019-07-22 12:56   ` [dpdk-dev] [PATCH v4 1/4] Revert "bus/pci: add Mellanox kernel driver type" David Marchand
2019-07-22 12:56   ` [dpdk-dev] [PATCH v4 2/4] eal: fix IOVA mode selection as VA for PCI drivers David Marchand
2019-11-25  9:33     ` Ferruh Yigit
2019-11-25 10:22       ` Thomas Monjalon
2019-11-25 12:03         ` Ferruh Yigit
2019-11-25 12:36           ` David Marchand
2019-11-25 12:58             ` Burakov, Anatoly
2019-11-25 14:29               ` Thomas Monjalon
2019-11-25 11:07       ` Jerin Jacob
2019-07-22 12:56   ` [dpdk-dev] [PATCH v4 3/4] drivers: change IOVA as VA PCI flag name David Marchand
2019-07-22 12:56   ` [dpdk-dev] [PATCH v4 4/4] eal: select IOVA as VA mode for default case David Marchand
2019-07-22 15:53   ` [dpdk-dev] [PATCH v4 0/4] Fixes on IOVA mode selection Thomas Monjalon
2019-07-23  3:35     ` Stojaczyk, Dariusz
2019-07-23  4:18       ` Jerin Jacob Kollanukkaran
2019-07-23  4:54         ` Stojaczyk, Dariusz
2019-07-23  5:27           ` Jerin Jacob Kollanukkaran
2019-07-23  7:21             ` Thomas Monjalon
2019-07-23  9:57             ` Burakov, Anatoly
2019-07-23 10:25               ` Thomas Monjalon
2019-07-23 13:56                 ` Burakov, Anatoly
2019-07-23 14:24                   ` [dpdk-dev] [EXT] " Jerin Jacob Kollanukkaran
2019-07-23 14:29                   ` [dpdk-dev] " Burakov, Anatoly
2019-07-23 14:36                     ` Jerin Jacob Kollanukkaran [this message]
2019-07-23 15:47                       ` [dpdk-dev] [EXT] " Burakov, Anatoly

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