- * In theory, an attempt to set the DMA mask to 64 and dma_using_dac=1
- * is the right thing. But some unclever PCIe drivers report it's OK
- * when the hardware drops those 64-bit PCIe packets. So trust
- * nobody and use 32 bits DMA addressing in any case.
+ * Some (old and buggy?) hardware drops 64-bit addressed PCIe packets,
+ * even when the PCIe driver claims that a 64-bit mask is OK. On the
+ * other hand, on some architectures, 64-bit addressing is mandatory.
+ * So go for the 64-bit mask only when failing is the other option.