X-Git-Url: http://www.chiark.greenend.org.uk/ucgi/~ianmdlvl/git?p=elogind.git;a=blobdiff_plain;f=docs%2Fudev_vs_devfs;h=9e803ca309b358caf9f4e712c6e9055eb2b24d37;hp=17853f881f6ed609b62f36834234634f2ef93a5c;hb=c1091150be0ae32584dcc1be20433a561928a30c;hpb=1237229594bf02f63922e481462efe0dae4294e4 diff --git a/docs/udev_vs_devfs b/docs/udev_vs_devfs index 17853f881..9e803ca30 100644 --- a/docs/udev_vs_devfs +++ b/docs/udev_vs_devfs @@ -13,7 +13,7 @@ Executive summary for those too lazy to read this whole thing: will be gladly ignored. -First off, some background. For a description of udev, and what it's +First off, some background. For a description of udev, and what its original design goals were, please see the OLS 2003 paper on udev, available at: @@ -26,7 +26,7 @@ directory. In that OLS paper, I described the current situation of a static /dev and the current problems that a number of people have with it. I also detailed how devfs tries to solve a number of these problems. In -hindsight, I should have never mentioned the word, devfs, when talking +hindsight, I should have never mentioned the word "devfs" when talking about udev. I did so only because it seemed like a good place to start with. Most people understood what devfs is, and what it does. To compare udev against it, showing how udev was more powerful, and a more @@ -90,7 +90,7 @@ And now for udev: to name devices in a persistent manner. More on that below. 4) udev emits D-BUS messages so that any other userspace program (like HAL) can listen to see what devices are created or removed. - It also allows userspace programs to query it's database to see + It also allows userspace programs to query its database to see what devices are present and what they are currently named as (providing a pointer into the sysfs tree for that specific device node.) @@ -101,7 +101,7 @@ And now for udev: want to deviate away from this standard (for example when naming some devices in a persistent manner), it is easily possible to do so. - 3) udev is small (49Kb binary) and is entirely in userspace, which + 3) udev is small and is entirely in userspace, which is swapable, and doesn't have to be running at all times. Nice, 7 out of 7 for udev. Makes you think the problems and constraints @@ -123,8 +123,8 @@ everything that devfs currently does, in about 6Kb of userspace code: Yes, that's right, 6Kb. So, you are asking, why are you still working on udev if it did everything devfs did back in May 2003? That's because just managing static device nodes based on what the kernel calls the -devices is _not_ the primary goal of udev. It's just a tiny side affect -of it's primary goal, the ability to never worry about major/minor +devices is _not_ the primary goal of udev. It's just a tiny side effect +of its primary goal, the ability to never worry about major/minor number assignments and provide the ability to achieve persistent device names if wanted. @@ -132,7 +132,7 @@ All the people wanting to bring up the udev vs. devfs argument go back and read the previous paragraph. Yes, all Gentoo users who keep filling up my inbox with smoking emails, I mean you. -So, how well does udev solve it's goals: +So, how well does udev solve its goals: Prevent users from ever worrying about major/minor numbers And here you were, not knowing you ever needed to worry about major/minor numbers in the first place, right? Ah, I see you @@ -146,7 +146,7 @@ So, how well does udev solve it's goals: As the above scenarios show, both desktop users and big iron users both need to not worry about which device is assigned to what major/minor device. - + udev doesn't care what major/minor number is assigned to a device. It merely takes the numbers that the kernel says it assigned to the device and creates a device node based on it, which the user can @@ -174,7 +174,7 @@ So, how well does udev solve it's goals: For more information on how to create udev rules to name devices, please see the udev man page, and look at the example udev rules that ship with the tarball. - + So, convinced already why you should use udev instead of devfs? No. Ok, fine, I'm not forcing you to abandon your bloated, stifling policy,