5 ms·

> It seems that for any operating system to be successful, it has to carry around POSIX compatibility like an extremely expensive entry pass. Curious - what ar

by barbs 10y ago

> It seems that for any operating system to be successful, it has to carry around POSIX compatibility like an extremely expensive entry pass. Curious - what are your main objections with POSIX? Is there another system you prefer?

JasonSage 10y ago
I mean, it sounds like his objection is that an operating system that doesn't have POSIX compatibility is dismissed out of hand. If we think of POSIX compatibility as something which is required in order for an operating system to be viable at any level, it means that there's a lot of energy in pioneering a new OS devoted to building up this compatibility simply so it can get some exposure. If we really want to encourage a fresh approach and disseminate new ideas, we need to move away from criterion like this and look more specifically at the principles and work being put forth and whether or not those are objectively successful or have merit. That's a much better way to move forward.
- caf 10y ago
  I think if you were building an OS an an academic research exercise and publishing papers based on it, no-one would object to your results on the basis of a lack of POSIX compatibility. The criteria is different if you're writing an OS for practical use with wide adoption, though. There, backward-compatibility is rightly considered a positive attribute - there is much existing software in the world, and the entire point of a practical OS is after all to run the software that people use. Exactly the same situation exists with CPUs. If you come up with a new micro-architecture that you actually want to sell to customers, you'd better come to the party with a C compiler and a ported OS or three.
gumby 10y ago
The best thing about POSIX at this point is back compatibility, nothing to be sneered at! But it carries a lot of (in retrospect) bad habits and decisions from the 60s and 70s as well as a tendency to redundancy due to some competing standards that were unified and need for some back compatibility. Now not everyone agrees on what is good and what is bad, so some experimentation in this area is good for everyone. Examples of what bother me include the ludicrousness of ioctl(), messed up / redundant semaphore semantics, ditto for IPC, primitive memory mgmt semantics, fork() -- a great hack for its time but since it's 99.9999% of the time followed by exec() should be split into separate address space and thread management), outdated and simultaneously simplistic and baroque security model(s), and various IO issues to many to go into in a HN comment. But my loathed feature is undoubtably someone else's sacred cow. As I said, letting more flowers bloom is in everybody's interest.
- CalChris 10y ago
  Well, I'm not going to disagree except to say that there are posix_spawn and vfork. I don't think anyone thinks the IPC solutions on offer are great but perhaps we should lower our expectations on that.
- dom0 10y ago
  I think the main issues with POSIX are: - (Correct) IO is ridiculously non-portable and painful in so many ways that it isn't even funny anymore - Locks are ridiculously non-portable and painful to the point where you're better off just using "mkdir" - POSIX is stuck in the "everything is bytes and we slap an encoding on it some of the time" era thinking. This makes it painful and hard to implement proper text handling in many instances. This also leads to a lot of bad behaviours. - Memory management is IMHO lacking from a user space perspective. For example, it's practically impossible to implement a cooperative memory cache on this. To the best of my knowledge no OS has the necessary interfaces, though. - ioctl as you mentioned - SysV/POSIX IPC is so bad that no one ever bothered actually using it for anything - Personally I think it's a misleading API (conceptually, see above, the text example for example) almost to the point of deceptiveness. It's very easy to write correct looking programs that behave far from intended, especially in edge cases. IMHO code using it is practically unreviewable in everything but the most trivial cases. Non-portability is practically guaranteed, you have to test every platform. Portable code usually turns out to be quite ugly due to platform deficiencies and minor API incompatibilities.
  - pdonis 10y ago
    > POSIX is stuck in the "everything is bytes and we slap an encoding on it some of the time" era thinking. I actually view this as a feature. Encoding/decoding of data should be an application level thing, not an OS-level thing. As far as the OS is concerned, data should be bytes. (Of course, it is true that, since POSIX defines a terminal spec, it has to at least specify how bytes are mapped to characters that print on the terminal. But I would rather see that removed altogether, so a terminal becomes just another application, than have an OS try to muck about with encodings.)

by barbs 10y ago

JasonSage 10y ago

I mean, it sounds like his objection is that an operating system that doesn't have POSIX compatibility is dismissed out of hand. If we think of POSIX compatibility as something which is required in order for an operating system to be viable at any level, it means that there's a lot of energy in pioneering a new OS devoted to building up this compatibility simply so it can get some exposure. If we really want to encourage a fresh approach and disseminate new ideas, we need to move away from criterion like this and look more specifically at the principles and work being put forth and whether or not those are objectively successful or have merit. That's a much better way to move forward.

caf 10y ago
I think if you were building an OS an an academic research exercise and publishing papers based on it, no-one would object to your results on the basis of a lack of POSIX compatibility. The criteria is different if you're writing an OS for practical use with wide adoption, though. There, backward-compatibility is rightly considered a positive attribute - there is much existing software in the world, and the entire point of a practical OS is after all to run the software that people use. Exactly the same situation exists with CPUs. If you come up with a new micro-architecture that you actually want to sell to customers, you'd better come to the party with a C compiler and a ported OS or three.

gumby 10y ago

The best thing about POSIX at this point is back compatibility, nothing to be sneered at! But it carries a lot of (in retrospect) bad habits and decisions from the 60s and 70s as well as a tendency to redundancy due to some competing standards that were unified and need for some back compatibility. Now not everyone agrees on what is good and what is bad, so some experimentation in this area is good for everyone. Examples of what bother me include the ludicrousness of ioctl(), messed up / redundant semaphore semantics, ditto for IPC, primitive memory mgmt semantics, fork() -- a great hack for its time but since it's 99.9999% of the time followed by exec() should be split into separate address space and thread management), outdated and simultaneously simplistic and baroque security model(s), and various IO issues to many to go into in a HN comment. But my loathed feature is undoubtably someone else's sacred cow. As I said, letting more flowers bloom is in everybody's interest.

CalChris 10y ago
Well, I'm not going to disagree except to say that there are posix_spawn and vfork. I don't think anyone thinks the IPC solutions on offer are great but perhaps we should lower our expectations on that.
dom0 10y ago
I think the main issues with POSIX are: - (Correct) IO is ridiculously non-portable and painful in so many ways that it isn't even funny anymore - Locks are ridiculously non-portable and painful to the point where you're better off just using "mkdir" - POSIX is stuck in the "everything is bytes and we slap an encoding on it some of the time" era thinking. This makes it painful and hard to implement proper text handling in many instances. This also leads to a lot of bad behaviours. - Memory management is IMHO lacking from a user space perspective. For example, it's practically impossible to implement a cooperative memory cache on this. To the best of my knowledge no OS has the necessary interfaces, though. - ioctl as you mentioned - SysV/POSIX IPC is so bad that no one ever bothered actually using it for anything - Personally I think it's a misleading API (conceptually, see above, the text example for example) almost to the point of deceptiveness. It's very easy to write correct looking programs that behave far from intended, especially in edge cases. IMHO code using it is practically unreviewable in everything but the most trivial cases. Non-portability is practically guaranteed, you have to test every platform. Portable code usually turns out to be quite ugly due to platform deficiencies and minor API incompatibilities.
- pdonis 10y ago
  > POSIX is stuck in the "everything is bytes and we slap an encoding on it some of the time" era thinking. I actually view this as a feature. Encoding/decoding of data should be an application level thing, not an OS-level thing. As far as the OS is concerned, data should be bytes. (Of course, it is true that, since POSIX defines a terminal spec, it has to at least specify how bytes are mapped to characters that print on the terminal. But I would rather see that removed altogether, so a terminal becomes just another application, than have an OS try to muck about with encodings.)