[TUHS] Any UNIX With No C In Userland?

[Greg A. Woods]

At Wed, 5 Mar 2025 10:54:01 +1100, Rob Pike <robpike at gmail.com> wrote:
Subject: [TUHS] Re: Any UNIX With No C In Userland?
>
> The notion that the struct layout must correspond to the hardware device's
> layout

Not "must" -- "can".

Of course that's just effectively using the compiler to do the
marshalling -- at compile time.

There are caveats of course -- one can lay out bit flags for a register
in a struct, but one must not make a pointer to such a struct and point
it at the register and expect bit manipulations to work -- even with -O0
you'll probably mess up any attempts to change bits predictably in that
register in ways that the hardware expects.

Of course the same problems occur if you try to point a word-sized
integer, even one with a "volatile" qualifier, at a register and
manipulate its bits with C bitwise expressions.

--
					Greg A. Woods <gwoods at acm.org>

Kelowna, BC     +1 250 762-7675           RoboHack <woods at robohack.ca>
Planix, Inc. <woods at planix.com>     Avoncote Farms <woods at avoncote.ca>
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