<div dir="ltr">Hi Arun,<div><br><div class="gmail_extra"><br><div class="gmail_quote">>On Thu, Jun 25, 2015 at 2:33 PM, Arun KS <span dir="ltr"><<a href="mailto:getarunks@gmail.com" target="_blank">getarunks@gmail.com</a>></span> wrote: >Hello Mudongliang,<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<span class=""><br>>On Tue, Jun 23, 2015 at 9:01 AM, 慕冬亮 <<a href="mailto:mudongliangabcd@gmail.com">mudongliangabcd@gmail.com</a>> wrote:<br>>><br>>> I know there are rarely float-point operations! What's the exception?<br>
> In the linux kernel, how does it handle the float-point operations in the >userland?<br>
<br>
</span>>>Most of the userspace programs do not use FP instructions. So by<br>>>default floating point engine is turned off during a context switch.<br>>>When a process executes floating point instruction, an undefined<br>>>exception is generated. Exception handler enables the floating point<br>>>engine and jump back to the same instruction which caused the<br>>>exception so that it will get re executed with FP engine on.<br>
<br>Is this somehow related to the platform in which linux runs? If the FP operations are valid, then will that still generate the exception or it does a context switch, turns on FP engine and re-executed?<br><br>
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