What is wrong with FreeBSD and USB Support

Hans Petter Selasky hps at selasky.org
Mon Mar 6 11:41:38 UTC 2017


On 03/06/17 12:36, Markus Rechberger wrote:
> libusb20 - usb userspace interface - usb - roundtrip problem that
> causes this high latency.

If you are using an old FreeBSD kernel, more than two years old, there 
was an issue where malloc() was used in the generic IOCTL path. This 
piece has in later versions of FreeBSD been replace with a conditional 
on-stack buffer. If you have this issue you should see high CPU usage on 
one of the CPU cores while doing USB transfers fast.


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