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Linus' comments are surprising to me. First, I would have thought that Rust is far too much like C++ for him. :-) Second, he seems remarkably calm about the v

Linus' comments are surprising to me. First, I would have thought that Rust is far too much like C++ for him. :-) Second, he seems remarkably calm about the very idea of a compiler inserting memory allocations in kernel code. He's only talking about panics. It's been a long time since I was involved in any kernel code, but invisible allocations would have set me (and any kernel programmers I knew) off worse than the worst rant anyone has ever seen from Linus. Any kind of invisible things (destructors, anyone?) would.

gpm 6y ago
> but invisible allocations would have set me (and any kernel programmers I knew) off worse than the worst rant anyone has ever seen from Linus Reading tea leaves here, but I think he's calm about this because he's pretty sure it's not happening (Which it isn't)
paavohtl 6y ago
Rust doesn't have invisible allocations. The compiler doesn't even know what an allocation is.
- mcguire 6y ago
  "So if the Rust compiler causes hidden allocations that cannot be caught and returned as errors, then I seriously think that this whole approach needs to be entirely NAK'ed, and the Rust infrastructure - whether at the compiler level or in the kernel wrappers - needs more work." So Linus is worried about nothing?
  - paavohtl 6y ago
    Yes, basically. The Rust standard library has data structures and functions which require memory allocation, and _will_ panic on allocation failure. But the allocating subset of the standard library is a separate module, which is usually turned off in embedded or kernel-level code. The current prototype uses it to speed up development, but the long term plan as far as I understand is to replace it or augment the current implementation to support fallible allocation (which is being worked on anyway).
mlindner 6y ago
> he seems remarkably calm about the very idea of a compiler inserting memory allocations in kernel code Rust doesn't insert memory allocations anywhere. You can use Rust without a heap even in stack-only environments. Just like C.

gpm 6y ago

> but invisible allocations would have set me (and any kernel programmers I knew) off worse than the worst rant anyone has ever seen from Linus Reading tea leaves here, but I think he's calm about this because he's pretty sure it's not happening (Which it isn't)

paavohtl 6y ago

Rust doesn't have invisible allocations. The compiler doesn't even know what an allocation is.

mcguire 6y ago
"So if the Rust compiler causes hidden allocations that cannot be caught and returned as errors, then I seriously think that this whole approach needs to be entirely NAK'ed, and the Rust infrastructure - whether at the compiler level or in the kernel wrappers - needs more work." So Linus is worried about nothing?
- paavohtl 6y ago
  Yes, basically. The Rust standard library has data structures and functions which require memory allocation, and _will_ panic on allocation failure. But the allocating subset of the standard library is a separate module, which is usually turned off in embedded or kernel-level code. The current prototype uses it to speed up development, but the long term plan as far as I understand is to replace it or augment the current implementation to support fallible allocation (which is being worked on anyway).

mlindner 6y ago

> he seems remarkably calm about the very idea of a compiler inserting memory allocations in kernel code Rust doesn't insert memory allocations anywhere. You can use Rust without a heap even in stack-only environments. Just like C.