On 8/10/22 11:35 AM, Michal Suchánek wrote: > On Wed, Aug 10, 2022 at 05:17:56PM +0200, Andrew Lunn wrote: >> > > I guess you are new to the netdev list :-) >> > > >> > > This is one of those FAQ sort of things, discussed every >> > > year. Anything like this is always NACKed. I don't see why this time >> > > should be any different. >> > > >> > > DSA is somewhat special because it is very old. It comes from before >> > > the times of DT. Its DT binding was proposed relatively earl in DT >> > > times, and would be rejected in modern days. But the rules of ABI mean >> > > the label property will be valid forever. But i very much doubt it >> > > will spread to interfaces in general. >> > >> > And if this is a FAQ maybe you can point to a summary (perhaps in >> > previous mail discusssion) that explains how to provide stable interface >> > names for Ethernet devices on a DT based platform? >> >> As far so the kernel is concerned, interface names are unstable. They >> have never been truly stable, but they have got more unstable in the >> past decade with multiple busses being probed in parallel, which did >> not happen before so much. >> >> > On x86 there is a name derived from the device location in the bus >> > topology >> >> This is nothing to do with x86. That is userspace, e.g. systemd, >> renaming the interfaces. This applies for any architecture for which >> systemd runs on. >> >> > which may be somewhat stable but it is not clear that it >> > cannot change, and there is an optional BIOS provided table that can >> > asssign meaningful names to the interfaces. >> >> I doubt the kernel is looking at ACPI tables. It is user space which >> does that. >> >> The kernel provides udev with a bunch of information about the >> interface, its bus location, MAC address, etc. Userspace can then >> decide what it wants to call it, and what its alternative names are, >> etc. >> >> Also, this is not just a network interface name problem. Any device >> with a number/letter in it is unstable. I2C bus devices: i2c0, >> i2c1... SPI bus deviceS: spi0, spi1..., > > Thees do have numbered aliases in the DT. I don't know if the kernel > uses them for anything. This is an issue for serial devices IMO. The only way to specify a stable console is to use its address! Things like /dev/ttyS0 can easily be reordered just by plugging/unplugging a card. You can of course add a udev rule to create some stable symlinks, but that's too late. >> Block devices, sda, sdb, sdc, > > These too, at least mmc. Which I am very grateful exists. While the block device situation is not as bad due to e.g. /dev/block/by-foo, it's still nice to be able to have a consistent name. --Sean
