Re: synching with minios

["Robert N. M. Watson" <robert.watson@xxxxxxxxxxxx>]

On 11 Dec 2012, at 10:25, Anil Madhavapeddy wrote:

> Absolutely. It just requires soft floating point support instead of hardware 
> calls.  This is available in the ARM backend already, but is an unusual 
> requirement for x86.
> 
> However, it's a requirement before we can merge Gabor Pali's FreeBSD kernel 
> backend into the main tree, so it's on the TODO list to sort out. Note that 
> most of the libraries we use only make occasional use of floating point 
> (unless they're explicit numerical computation libraries), so this won't be a 
> performance hit either.

The usual in-kernel workaround is to use a very small amount of fixed-point 
rather than depend on the presence of floating point -- not just to avoid the 
functional footprint, but for performance reasons. This is not the ideal 
solution for everyone, but I do find myself slightly surprised that the base 
OCaml runtime *must* use FP. You should be able to measure the additional cost 
on VM/OS context switching with FP enabled as a result. (At least, I would 
surmise.)

Robert