Some additional information. I have run an strace of the "xl migrate-receive" process on servers with xen-utils-4.4 4.4.1-9+deb8u4 (which fails) and 4.4.1-9+deb8u3 (which works).
On systems with 4.4.1-9+deb8u4 installed, strace shows exactly 395 lines like this one: ioctl(5, SNDCTL_DSP_RESET, 0x7ffeb47b44b0) = -1 EAGAIN (Resource temporarily unavailable) On systems with 4.4.1-9+deb8u3 installed, these hundreds of lines do not appear at all - on servers that have identical hardware as those running 4.4.1-9+deb8u4. I can provide the entire strace output if needed.
