[PATCH v5.2 10/12] termios: add new baud_t interface, defined to be explicitly numeric

[Adhemerval Zanella Netto]

On 29/05/25 16:55, H. Peter Anvin wrote:
> On May 29, 2025 11:55:01 AM PDT, Adhemerval Zanella Netto <adhemerval.zanella@linaro.org> wrote:
>>
>>
>> On 27/05/25 19:08, H. Peter Anvin wrote:

> Ugh, I hate to bikeshed my own proposal, but I'm kind of wondering if we ought to make baud_t either a 64-bit or a floating-point type right off the bat, even if none of the kernels can take advantage of it for now. Anyone had thoughts on that?
> 

I don't think a floating-point would improve things here, the kernel interface
would most likely always use integers and libc will need to so the transformation
anyway. Also, I don't think we will easily seen speed_t requirement larger than
UITN64_MAX anytime soon.

Using uint64_t would require to rethink the interface idea, since now you document
that cfgetXspeed get/set the speed_t from the termios struct and changing it size
would require to either change termios or add a new termios2.  Both options seems
to add a lot of work that would be used only in future expansions.

> If nothing else I will rewrite the definition a little to say that speed_t == baud_t is not something that is guaranteed in the future.