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 14:24:28 +0000 [thread overview]
Message-ID: <BYAPR18MB2424557B37B49D11E748FF64C8C70@BYAPR18MB2424.namprd18.prod.outlook.com> (raw)
In-Reply-To: <751d0163-ed33-e05b-dd24-386055114384@intel.com>
> -----Original Message-----
> From: Burakov, Anatoly <anatoly.burakov@intel.com>
> Sent: Tuesday, July 23, 2019 7:27 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 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-
> sysfs.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?
I checked with a x86 and arm64 machine. I could not see "/sys/devices/virtual/iommu"
But looks like "/sys/class/iommu/" present when iommu present.
$ uname -a
Linux jerin-lab 5.1.15-arch1-1-ARCH #1 SMP PREEMPT Tue Jun 25 04:49:39 UTC 2019 x86_64 GNU/Linux
$ ls /sys/devices/virtual/
bdi dmi drm graphics mem misc msr net powercap thermal tty vc vtconsole workqueue
# ls /sys/class/iommu/
# uname -a
Linux alarm 4.14.76-5.0.0-g12f0519 #63 SMP PREEMPT Thu Jul 11 17:43:54 IST 2019 aarch64 GNU/Linux
# ls /sys/devices/virtual/
bdi block graphics input mem misc net otx-bphy-ctr otx-gpio-ctr ppp tty vc vfio vtconsole workqueue
# ls /sys/class/iommu/
smmu3.0x0000830000000000
>
> --
> Thanks,
> Anatoly
next prev parent reply other threads:[~2019-07-23 14:24 UTC|newest]
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 ` Jerin Jacob Kollanukkaran [this message]
2019-07-23 14:29 ` Burakov, Anatoly
2019-07-23 14:36 ` [dpdk-dev] [EXT] " Jerin Jacob Kollanukkaran
2019-07-23 15:47 ` Burakov, Anatoly
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