Re: port-amd64/42980: satalink DMA fails under amd64

[Julian Bourne <julian.bourne%gmail.com@localhost>]

OK, I verified several things with the 5.0.2 kernel:

(1) amd64 GENERIC (non xen) suffers as well
(2) amd64 XEN_DOM0 suffers with or without Manuel's patch
(3) uvm_pglistalloc has the boundary >= size check as well

See trace I added to the code from my kernel logs:

../../../../arch/xen/x86/xen_bus_dma.c:259
  uvm_pglistalloc failed error=22, size=65536,
  alignment=4096, boundary=8192.
satalink0:0: unable to create xfer table DMA map
  for drive 0, error=22
wd0(satalink0:0:0): using PIO mode 4

Hope that helps.

If I can throw in 2c, I think the problem is that the bouncebuf
create call should be using the max segment size from the sc
structure, not MAXPHYS, but I admit, I'm way out of my depth.