On Fri, Jan 17, 2014 at 12:23 PM, Christopher Ahrens <n...@leviacomm.net>wrote:
> Kevin Lyda wrote: > >> Regarding the "less architecture support to save electricity" >> argument, I'm not sure one follows the other. Computing power has >> grown to a point that emulators are perfectly valid - particularly for >> older systems. >> >> I think a push to package and maintain emulators for many of these >> older architectures would be beneficial in many ways. There's some >> amount of this already - there are instructions for the simh simulator >> for the VAX arch for instance. The obvious benefits I couldd see would >> be: >> >> 1) You could spin up builds on them w/ little to no effect on electricity >> usage. >> 2) Even if the OpenBSD foundation's arch X machine dies, there would >> still be infrastructure to maintain the port. >> 3) It would widen the possible number of developers if people could >> spin up older architectures in an emulator. >> 4) It would make OpenBSD a valuable tool for accessing older media and >> documenting older architectures. >> >> I know emulators are not perfect, so a physical machine would be >> superior. But if there was some encouragement for emulators for archs >> I think those would be useful benefits. >> >> > > Even if emulators did work, you still have a couple of problems: > > *Instructions are executed as they should, not how they actually work > *instructions will, at best, take a two instructions on the host if > the architectures and endianness match; if not: > The instruction has to matched against a lookup table and if there > is a single equivalent instruction to do the same thing and you have > the same endianness, that is three processors cycles. If its > different endianness, then you now have between 32 and 128 more > instructions (convert to the host endianness then back for 16 to > 64-bit archs) > Now if there isn't an equivalent instructions (welcome to the > difference between CISC and RISC machines) you are probably going to > have to run two all the way up to a couple dozen instructions to > emulate just one, plus you still have the same problem with > endianness like before > *assuming all the above works, you are still tripling the effort in > debugging because now you have to determine if the bug is in the > emulated environment, the emulator itself, or the host OS. > *Even if the above still works perfectly, you will still miss all the > bugs caused by memory alignment (the host will fix any of that), which > are the most common we find or the host ends up adding new ones. > > But all this is ignoring the real purpose of running on real hardware > which is that the same code runs on all the boxes, so if one of them > outputs something unexpected from the other machines, we know something > is wrong. > > The only way to reduce our power for the older archs is if someone were > able to re-build the entire system on more power-efficient, > bug-compatible chips > > Support for multiple archs brings interest and exposes bad code in >> ways limited arch support does not. >> > > Exactly > > Dropping that to save electricity >> is not a valid reason with today's compute power. >> >> Anyway, it's been a long time since I did stuff with OpenBSD, but I >> think it would be a shame to drop such support. So I'll back up my >> words with some cash. And if I get a roundtuit, perhaps some code or >> docs as well. >> > > Please continue to do this. Cash, code and correct docs help OpenBSD, > dreaming doesn't. > > >> Kevin >> >> > > And now to paraphrase Theo: > Shut up, donate, and hack. > > >Please continue to do this. Cash, code and correct docs help OpenBSD, dreaming doesn't. I've donated $20 a month in perpetuity via http://www.openbsdfoundation.org/donations.html. The community needs less than 99 other donors willing to admit that OpenBSD is worth more than a pizza. This doesn't even begin to make up for the benefit I've received from the project, but it is a start. A small suggested change to the OpenBSD.org page header- put a donate button and a small message under the header picture. "We need X financial maintainers @ $20 a month." I completely forgot that I could donate until I saw this thread come up on reddit.com/r/programming, and it didn't even occur to me that I should be donating monthly until I read the thread. Sometimes, you just have to be that obvious to people, and it may be easier to ask for a few new donors every so often than to be beholden to a single large donor.
