Hi Manish Regmi, My colleague said he doesn't know it the buffer start address and size are aligning the block size. I'll make the test next week... :-) Thanks and regards, Colin ----- Original Message ----- From: "Manish Regmi" <regmi.manish@xxxxxxxxx> To: "colin" <colin@xxxxxxxxxxxxxx> Cc: <kernelnewbies@xxxxxxxxxxxx> Sent: Friday, December 22, 2006 1:26 PM Subject: Re: How to know the file size limit, and know if O_DIRECT is supported > On 12/22/06, colin <colin@xxxxxxxxxxxxxx> wrote: > > > > Hi Erik, > > My colleague said that when use direct I/O on USB disk that has a ext3 > > partition, open can succeed, but read fails. > > I know that filesystem must have some system calls for direct I/O, and open > > with O_DIRECT flag will check if these system calls exist. > > But why does read fail? Is it that direst I/O cannot use on USB disk? > > Have you aligned the buffers correctly. Read/Write will fail if buffer > is not aligned in sector boundry. > > -- > --------------------------------------------------------------- > regards > Manish Regmi > > --------------------------------------------------------------- > UNIX without a C Compiler is like eating Spaghetti with your mouth > sewn shut. It just doesn't make sense. -- Kernelnewbies: Help each other learn about the Linux kernel. Archive: http://mail.nl.linux.org/kernelnewbies/ FAQ: http://kernelnewbies.org/faq/
