On Mon, Mar 23, 2009 at 21:39, David Brownell <david-b@xxxxxxxxxxx> wrote: > On Monday 23 March 2009, Kay Sievers wrote: >> > OTP data in lot of the NAND chips I have here exceeds the sysfs 4KB >> > binary file limit; 20KB commonly, 128KB for OneNand. >> >> There is no such limit for binary sysfs files. We have many large file >> there, which map such sizes. > > Odd, just the other day I created one with actual size of 8KB. > But "ls -l" showed 4K. There are larger files: $ ls -l /sys/devices/pci .../usb1/1-1/descriptors -r--r--r-- 1 root root 65553 2009-03-23 22:12 ... /usb1/1-1/descriptors > That's clearly a limit... and "cp" was > unable to read the whole thing, it stopped at 4K. "dd" could > read everything though: dd bs=1k count=8 did it. Some larger files seem to work here: $ ls -l /sys/devices/pci0000:00/0000:00:02.0/rom -r-------- 1 root root 131072 2009-03-23 22:13 /sys/devices/pci ... $ cat /sys/devices/pci0000:00/0000:00:02.0/rom | wc -c 65536 $ dd if=/sys/devices/.../rom of=/dev/null bs=1 65536+0 records in 65536+0 records out 65536 bytes (66 kB) copied, 0.103753 s, 632 kB/s > Something seems odd with binary sysfs files in general. I've > observed something zapping size down to zero after userspace > did some oddball reads ... of the "past EOF" variety, ISTR. Hmm, never seen such a thing, but the logic is implemented per-file, so it might be something that should be fixed in the driver that created the file. Kay -- To unsubscribe from this list: send the line "unsubscribe linux-hotplug" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
