Brian Norris wrote: > Well, today you're in luck! You're touching a driver that requires no > special hardware, so you should be able to test it.
> I think you can try using the mem= kernel parameter (see > Documentation/kernel-parameters.txt) to restrict your system memory, and > then try using that unreachable portions of memory for phram. You can > try this driver as either a module or built-in. For the former, you can > specify the parameters during modprobe time, or later by writing to > /sys/module/phram/parameters/phram. For the latter, you can specify on > the kernel command line or in /sys/module/phram/parameters/phram. > Let me know if you have any more questions about testing your patch. Hi Brian, As you have suggested I have restricted my laptop's memory to 1GB and tried to access unreachable portion of memory(2GB). It seems to be successfully registered(this is OK right ?). I have also tested below error scenarios; all exiting gracefully - parameter too long - too many arguments - not enough arguments - invalid start adddress - invalid device length This is my first interaction with phram device so I request you to verify my testing. Below are the commands and output I did for this testing. ----------------------------------------------------- <restricting memory of my machine to 1 GB> saurabh@saurabh:~/little/Task02/linux$ cat /proc/meminfo | grep Mem MemTotal: 1016588 kB MemFree: 126016 kB MemAvailable: 295508 kB saurabh@saurabh:~/little/Task02/linux$ cat /proc/cmdline BOOT_IMAGE=/boot/vmlinuz-4.3.0-10333-gdfe4330-dirty mem=1024M root=UUID=2b66d4b2-ac21-4554-bf3b-64bc973e1dad ro quiet splash vt.handoff=7 <accessing unreachable portions of memory> saurabh@saurabh:~/little/Task02/linux$ sudo insmod drivers/mtd/devices/phram.ko phram=ram,2048Mi,1ki saurabh@saurabh:~/little/Task02/linux$ sudo dmesg -c [ 634.748495] phram: ram device: 0x400 at 0x80000000 <parameter too long> saurabh@saurabh:~/little/Task02/linux$ sudo insmod drivers/mtd/devices/phram.ko phram=abcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyz,256Mi,1Mi insmod: ERROR: could not insert module drivers/mtd/devices/phram.ko: Invalid parameters saurabh@saurabh:~/little/Task02/linux$ sudo dmesg -c [ 1469.763787] phram: parameter too long [ 1469.763797] phram: `abcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyz,256Mi,1Mi' invalid for parameter `phram' <too many arguments> saurabh@saurabh:~/little/Task02/linux$ sudo insmod drivers/mtd/devices/phram.ko phram=swap,256Mi,1Mi,extra_parameter insmod: ERROR: could not insert module drivers/mtd/devices/phram.ko: Invalid parameters saurabh@saurabh:~/little/Task02/linux$ sudo dmesg -c [ 1650.081694] phram: too many arguments [ 1650.081703] phram: `swap,256Mi,1Mi,extra_parameter' invalid for parameter `phram' <not enough arguments> saurabh@saurabh:~/little/Task02/linux$ sudo insmod drivers/mtd/devices/phram.ko phram=swap,256Mi insmod: ERROR: could not insert module drivers/mtd/devices/phram.ko: Invalid parameters saurabh@saurabh:~/little/Task02/linux$ sudo dmesg -c [ 1707.437130] phram: not enough arguments [ 1707.437138] phram: `swap,256Mi' invalid for parameter `phram' <invalid start address> saurabh@saurabh:~/little/Task02/linux$ sudo insmod drivers/mtd/devices/phram.ko phram=swap,256xyz,1Mi insmod: ERROR: could not insert module drivers/mtd/devices/phram.ko: Invalid parameters saurabh@saurabh:~/little/Task02/linux$ sudo dmesg -c [ 1783.014351] phram: invalid start address [ 1783.014359] phram: `swap,256xyz,1Mi' invalid for parameter `phram' <invalid device length> saurabh@saurabh:~/little/Task02/linux$ sudo insmod drivers/mtd/devices/phram.ko phram=swap,256Mi,1xyz insmod: ERROR: could not insert module drivers/mtd/devices/phram.ko: Invalid parameters saurabh@saurabh:~/little/Task02/linux$ sudo dmesg -c [ 1831.746108] phram: invalid device length [ 1831.746117] phram: `swap,256Mi,1xyz' invalid for parameter `phram' ------------------------------------------- -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
