floating points in kernel space

[lei yang]

How can I know arm kernel has suppored hardware float point?
is there a kernel config to be enabled for this supporting?

Lei

On Wed, Jan 5, 2011 at 7:26 AM, julie Sullivan <kernelmail.jms at gmail.com> wrote:
>
>> I think the issue is the kernel is extremely concerned with the
>> efficiency of the syscall path.
>>
>> Very legitimately some benchmarks just measure that one path to see
>> how many thousands of syscalls per second can be made.
>>
>> To accelerate that path as much as possible, the linux kenel chooses
>> not to incur the overhead of preserving the FP registers on every
>> syscall.
>>
>> So kernel code that uses FP must first ensure any registers it uses
>> are preserved.  I don't recall ever writing any FP kernel code, so I
>> don't know what facilities are available to do that.
>>
>> Greg
>
> Greg
>
> I had a vague idea about overhead being incurred due to the mode switch, but
> your clear explanation makes it a lot easier to understand _where_ this
> happens.
> It's very helpful, thank you for your response.
>
> Julie
>
>
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