----- Original Message ----- From: "Gleb O. Raiko" <raiko@xxxxxxxxxxxx> To: "wuming" <wuming@xxxxxxxxx> Cc: <linux-mips@xxxxxxxxxxxxxx> Sent: Monday, December 20, 2004 4:43 PM Subject: Re: problem about dma > In 2.4, memcpy's prefetch may (and, in practice, do, no smiles, it cost > me a lot of time to realize) access that memory. I though it has been > fixed in 2.6 someday. > > Regards, > Gleb. > Thank you! :) But I think it is not the only reason, because the CPU on my platform does not support the "pref" instruction. So, memcpy's prefetch may have no effect on that arrange of memory.