Date: Fri, 3 Jun 2016 22:24:00 +0200 From: Hans Petter Selasky <hps@selasky.org> To: KILOREUX Emperex <kiloreux@gmail.com>, freebsd-arch@freebsd.org Cc: Koop Mast <kwm@freebsd.org>, eadler@freebsd.org, =?UTF-8?Q?Jean-S=c3=a9bastien_P=c3=a9dron?= <dumbbell@freebsd.org> Subject: Re: API to link sysctl nodes to devices Message-ID: <6b21329d-33ea-e628-b06c-27a744c9ec09@selasky.org> In-Reply-To: <CAN1JrQ2dd0WZi0_aaNdqH9xdy292tP2DYLxvKV9bfK93vYFLXw@mail.gmail.com> References: <CAN1JrQ2dd0WZi0_aaNdqH9xdy292tP2DYLxvKV9bfK93vYFLXw@mail.gmail.com>
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Hi, On 06/03/16 19:14, KILOREUX Emperex wrote: > Hey, > > As part of my participation GSOC, I have been working on an API spec to > link sysctl nodes to devices. > Can you clarify a bit what you mean by "device". The term "device" was a bit too generic for me :-) I suppose you mean a "character device", right? Can you give some examples of properties for a character device, which can be exposed trough these sysctls you propose ? > And I cam up with few ideas that I need some feedback on before proceeding > to the implementation on the kernel. > > - We need devices to have their propoer sysctl trees, and thus every device > linked will have its own id as the head of its syctl tree. > > For example a device with id 0x94, would have it's sysctl root look like > dev.fs.0x94 where the below parameters can be accessed after that. Would it be better to have a direct mapping between character device name, including directories and dev.fs.xxx , like /dev/cuaU0 maps to dev.fs.cuaU0.xxx ? > > - We want to give device drivers the ability to create and delete sysctl > nodes as they want, thus proposing a proper interface for it. > > > So I have been thinking so far to enable the creation of the root for those > sysctl nodes on the system initialization, to allow existing device drivers > to link their device on the tree. > > Also we want to propose a new function similar to make_dev, supposed we > name it make_dev_sys, that gets the device id and links it on the tree of > existing sysctl nodes, and for the purpose of keeping track of the > available sysctl nodes for each device, I thought of proposing a change to > the device switching table "cdevsw" to keep systcl context tracked for the > device. > > Would any modification to cdevsw break backward compatibility ? > Please provide us with any feedback you have on this proposition and any > defects you seeing in the logic. > > Your help is much appreciated. --HPS
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