From: Cornelia Huck <cohuck@redhat.com> To: Alex Williamson <alex.williamson@redhat.com> Cc: "Matthew Rosato" <mjrosato@linux.ibm.com>, "kvm@vger.kernel.org" <kvm@vger.kernel.org>, "Libvirt Devel" <libvir-list@redhat.com>, "Kirti Wankhede" <kwankhede@nvidia.com>, "Erik Skultety" <eskultet@redhat.com>, "Pavel Hrdina" <phrdina@redhat.com>, "Daniel P. Berrangé" <berrange@redhat.com>, "Sylvain Bauza" <sbauza@redhat.com>, "Christophe de Dinechin" <dinechin@redhat.com>, "Tony Krowiak" <akrowiak@linux.ibm.com> Subject: Re: mdevctl: A shoestring mediated device management and persistence utility Date: Fri, 28 Jun 2019 11:06:48 +0200 Message-ID: <20190628110648.40e0607d.cohuck@redhat.com> (raw) In-Reply-To: <20190627195704.66be88c8@x1.home> On Thu, 27 Jun 2019 19:57:04 -0600 Alex Williamson <alex.williamson@redhat.com> wrote: > On Thu, 27 Jun 2019 15:15:02 -0600 > Alex Williamson <alex.williamson@redhat.com> wrote: > > > On Thu, 27 Jun 2019 09:38:32 -0600 > > Alex Williamson <alex.williamson@redhat.com> wrote: > > > > On 6/27/19 8:26 AM, Cornelia Huck wrote: > > > > > > > > > > { > > > > > "foo": "1", > > > > > "bar": "42", > > > > > "baz": { > > > > > "depends": ["foo", "bar"], > > > > > "value": "plahh" > > > > > } > > > > > } > > > > > > > > > > Something like that? > > > > > > I'm not sure yet. I think we need to look at what's feasible (and > > > easy) with jq. Thanks, > > > > I think it's not too much trouble to remove and insert into arrays, so > > what if we were to define the config as: > > > > { > > "mdev_type":"vendor-type", > > "start":"auto", > > "attrs": [ > > {"attrX":["Xvalue1","Xvalue2"]}, > > {"dir/attrY": "Yvalue1"}, > > {"attrX": "Xvalue3"} > > ] > > } > > > > "attr" here would define sysfs attributes under the device. The array > > would be processed in order, so in the above example we'd do the > > following: > > > > 1. echo Xvalue1 > attrX > > 2. echo Xvalue2 > attrX > > 3. echo Yvalue1 > dir/attrY > > 4. echo Xvalue3 > attrX > > > > When starting the device mdevctl would simply walk the array, if the > > attribute key exists write the value(s). If a write fails or the > > attribute doesn't exist, remove the device and report error. Yes, I think it makes sense to fail the startup of a device where we cannot set all attributes to the requested values. > > > > I think it's easiest with jq to manipulate arrays by removing and > > inserting by index. Also if we end up with something like above, it's > > ambiguous if we reference the "attrX" key. So perhaps we add the > > following options to the modify command: > > > > --addattr=ATTRIBUTE --delattr --index=INDEX --value=VALUE1[,VALUE2] > > > > We could handle it like a stack, so if --index is not supplied, add to > > the end or remove from the end. If --index is provided, delete that > > index or add the attribute at that index. So if you had the above and > > wanted to remove Xvalue1 but keep the ordering, you'd do: > > > > --delattr --index=0 > > --addattr --index=0 --value=Xvalue2 > > > > Which should results in: > > > > "attrs": [ > > {"attrX": "Xvalue2"}, > > {"dir/attrY": "Yvalue1"}, > > {"attrX": "Xvalue3"} > > ] Modifying by index looks reasonable; I just sent a pull request to print the index of an attribute out as well, so it is easier to specify the right attribute to modify. > > > > If we want to modify a running device, I'm thinking we probably want a > > new command and options --attr=ATTRIBUTE --value=VALUE might suffice. > > > > Do we need to support something like this for the 'start' command or > > should we leave that for simple devices and require a sequence of: > > > > # mdevctl define ... > > # mdevctl modify --addattr... > > ... > > # mdevctl start > > # mdevctl undefine > > > > This is effectively the long way to get a transient device. Otherwise > > we'd need to figure out how to have --attr --value appear multiple > > times on the start command line. Thanks, What do you think of a way to specify JSON for the attributes directly on the command line? Or would it be better to just edit the config files directly? > > This is now implemented, and yes you can specify '--addattr remove > --value 1' and mdevctl will immediately remove the device after it's > created (more power to the admin). Listing defined devices also lists Fun ;) > any attributes defined for easy inspection. It is also possible to > override the conversion of comma separated values into an array by > encoding and escaping the comma. It's a little cumbersome, but > possible in case a driver isn't fully on board with the one attribute, > one value rule of sysfs. Does this work for vfio-ap? I also still I do not have ap devices to actually test this with; but defining a device and adding attributes seems to work. > need to check if this allows an NVIDIA vGPU mdev to be configured such > that the framerate limiter can be automatically controlled. Thanks, > > Alex
next prev parent reply index Thread overview: 46+ messages / expand[flat|nested] mbox.gz Atom feed top 2019-05-23 23:20 Alex Williamson 2019-05-24 10:11 ` Cornelia Huck 2019-05-24 14:43 ` Alex Williamson 2019-06-07 16:06 ` Halil Pasic 2019-06-11 19:45 ` Cornelia Huck 2019-06-11 20:28 ` Alex Williamson 2019-06-12 7:14 ` Cornelia Huck 2019-06-12 15:54 ` Halil Pasic 2019-06-13 10:02 ` Cornelia Huck 2019-06-12 15:07 ` Halil Pasic 2019-06-13 16:17 ` Christophe de Dinechin 2019-06-13 16:35 ` Alex Williamson 2019-06-14 9:54 ` [libvirt] " Christophe de Dinechin 2019-06-14 14:23 ` Alex Williamson 2019-06-14 15:06 ` Christophe de Dinechin 2019-06-14 16:04 ` Alex Williamson 2019-06-17 16:03 ` Cornelia Huck 2019-06-17 14:00 ` Daniel P. Berrangé 2019-06-17 14:54 ` Alex Williamson 2019-06-17 15:10 ` Daniel P. Berrangé 2019-06-17 17:05 ` Alex Williamson 2019-06-18 8:44 ` Daniel P. Berrangé 2019-06-18 11:01 ` Cornelia Huck [not found] ` <CALOCmukPWiXiM+mN0hCTvSwfdHy5UdERU8WnvOXiBrMQ9tH3VA@mail.gmail.com> 2019-06-18 22:12 ` Alex Williamson 2019-06-19 7:28 ` Daniel P. Berrangé 2019-06-19 9:46 ` Cornelia Huck 2019-06-19 18:46 ` Alex Williamson 2019-06-20 8:24 ` Daniel P. Berrangé [not found] ` <CALOCmu=6Xmw-_-SVXujCEcgPY2CQiBQKgfUMJ45WnZ_9XORyUw@mail.gmail.com> 2019-06-19 9:57 ` Cornelia Huck 2019-06-19 19:53 ` Alex Williamson 2019-06-25 22:52 ` Alex Williamson 2019-06-26 9:58 ` Cornelia Huck 2019-06-26 14:37 ` Alex Williamson 2019-06-27 1:53 ` Alex Williamson 2019-06-27 12:26 ` Cornelia Huck 2019-06-27 15:00 ` Matthew Rosato 2019-06-27 15:38 ` Alex Williamson 2019-06-27 16:13 ` Matthew Rosato 2019-06-27 21:15 ` Alex Williamson 2019-06-28 1:57 ` Alex Williamson 2019-06-28 9:06 ` Cornelia Huck [this message] 2019-06-28 14:01 ` Matthew Rosato 2019-06-28 17:05 ` Alex Williamson 2019-07-01 8:20 ` Cornelia Huck 2019-07-01 14:40 ` Alex Williamson 2019-07-01 17:13 ` Cornelia Huck
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