Is this a GPL violation case?

[Torsten Schlabach]

Dear list!

At a customer site, I came across an embedded Linux system which is 
built upon uCLinux, http://www.uclinux.org/.

The vendor of the system does not provide any pointers to the GPL at 
all; at least not that I would be aware of.

Unfortunately, I cannot find any license info about uCLinux as well. Is 
it sufficient that uCLinux contains the Linux kernel for the GPL to be 
applicable to uCLinux and would that then apply to the proprietary 
vendor product as well?

Regards,
Torsten