Am 02.09.2018 um 18:40 schrieb Andreas Färber:
Am 02.09.2018 um 11:28 schrieb Stefan Seyfried:
Am 02.09.2018 um 07:23 schrieb Simon Lees:
Personally I think 4 is too low, especially for those who have worked in electrical engineering contexts, at my last job I commonly had 8-10 ports sometimes more, this was partly because I had a 8 port moxa box
boot parameter 8250.nr_uarts=32 will give you the old behaviour back.
Granted I'm an extreme case but given makers / hackers are one of our target audiences I can easily see some of them frequently using more then 4.
I can easily see them adding a simple boot parameter :-)
Really?
Yes, i can imagine that someone who is able to put a 200+$ PCIE card into his machine is also able to find out about the boot parameter.
I've just been faced with this topic on arm64. I came to the conclusion, based on what is there for x86_64 and others, that it's much easier for me and other users that mind it to _lower_ the number of ttyS devices via /etc/default/grub config than to run into situations where the port you expect just doesn't show up and you don't know why.
Well, but on arm almost every board still has its own kconfig (and probably still no hot-pluggable serial port cards), so it of course makes sense to then set the default to a number of ports thats likely to be available.
[...] The present ttyS devices seem an ugliness specific to the 8250 driver, and jslaby's argumentation for having them around doesn't apply to other architectures or at least I don't see why this one subsystem should allow to override any ACPI/DT-supplied configuration. Getting 8250 more in line with other serial drivers so that ttyS devices only show up after initialized (think ttyUSB) would be the most elegant solution, and I assume the number of users complaining would be as low as those complaining about NR_CPUS being higher than their respective system has.
Certainly, that would be the best solution, as only devices that have actual hardware present would show up.
Until then, keeping a high default seems safest for those that may want to hot-plug ports and for whom rebooting to bump 8250.nr_uarts would be inconvenient. Keep in mind not every openSUSE user runs a desktop. It'll also save kernel engineers from "invalid" Bugzilla tickets.
Do you know of any hot-plug capable, 8250-driven serial port cards? I don't. The only hot-pluggable serial cards I know of are (rather old nowadays) 3G/UMTS ExpressCards, but those actually are implemented on the USB part of ExpressCard, not PCIE and thus are driven by usbserial. (Yes, I know that there are servers that can do PCI or PCIE hotplugging, but I don't deem them "common" or relevant to this discussion). -- Stefan Seyfried "For a successful technology, reality must take precedence over public relations, for nature cannot be fooled." -- Richard Feynman -- To unsubscribe, e-mail: opensuse-factory+unsubscribe@opensuse.org To contact the owner, e-mail: opensuse-factory+owner@opensuse.org