Limits to seeding /dev/random | random(4)

[Dirk-Willem van Gulik]

When feeding /dev/random from hardware USB devices like Bill Woodcock’s design in PCB incarnation:

	https://13-37.org/de/shop/infinite-noise-trng/

Are there any caveats with regard to volume or speed of doing so ? Or is it always a plus ? 

Actual code at https://github.com/dirkx/infnoise/blob/master/software/libinfnoise.c line 122:

	if ((devRandomFD = open("/dev/random",O_WRONLY)) <0)
		.. error handling

	if (write(devRandomFD, bytes, length) != length) 
		.. error handling

And is there any case where length would not return the length written — it seems that the driver traps/ignores EINT, EAGAIN and short writes ? 

Or should one check the entropy available in /dev/random (how?) and hold off feeding it until it is low enough (this is what the infinite-trng seems to do on linux).

With kind regards,

Dw