Character, block and USB drivers

1. cd lab15_1; make builds sysbuf_starter.ko and the static test program sbtest
2. TODO 1 init: alloc_chrdev_region, cdev_init/cdev_add, class_create, device_create (with the goto ladder)
3. TODO 2 read: EOF, min, copy_to_user, *pos += n
4. TODO 3 write: −ENOSPC, copy_from_user, update used
5. TODO 4 ioctl: CLEAR, GETSIZE with put_user, default −ENOTTY
6. ../guest/run_guest.sh . then insmod, echo, cat, dd, ./sbtest

the starter, before TODO 1 (real)

$ insmod sysbuf_starter.ko; echo status $?
insmod: can't insert 'sysbuf_starter.ko': No such device
status 19
$ dmesg | grep sysbuf
sysbuf: not registered yet: TODO 1

the finished lab (real)

$ ./sbtest
write: 22 bytes, size now 22
read at offset 14: 8 bytes "Barishal"
read again: 0 (end of file)
ioctl 0x1234: Inappropriate ioctl for device
SYSBUF_GETSIZE = 0x80045302  (_IOR('S', 2, int))

1. cd lab15_2; make builds sbd_starter.ko
2. TODO 2 tag set and disk: blk_mq_alloc_sq_tag_set, sbd_alloc_disk, fill major, minors, fops, name
3. TODO 3 set_capacity in sectors, add_disk; jump to the right undo label on error
4. TODO 1 queue_rq: rq_for_each_segment, bvec_kmap_local, memcpy in the right direction
5. test: mke2fs -q /dev/sbd0; mount /dev/sbd0 /mnt, write a file, umount, mount again, read it
6. echo 1 > /sys/module/sbd_starter/parameters/trace and watch your requests in dmesg

the starter, before TODO 2–3 (real)

$ insmod sbd_starter.ko; echo status $?
insmod: can't insert 'sbd_starter.ko': No such device
status 19
$ dmesg | grep sbd | tail -1
sbd: no disk yet: TODO 2 and 3

the finished lab (real)

$ insmod sbd.ko
$ mke2fs -q /dev/sbd0 && mount /dev/sbd0 /mnt
$ echo hi > /mnt/f && cat /mnt/f && umount /mnt
Filesystem label=   …
4096 inodes, 16384 blocks
2 block groups
hi

1. cd lab15_3; make builds sysprog_kbd_starter.ko and mylsusb
2. USB=1 ../guest/run_guest.sh . adds a UHCI controller, a USB keyboard and a mouse; run mylsusb
3. TODO 1 id_table; TODO 2 find the interrupt IN endpoint
4. TODO 3 usb_fill_int_urb, usb_set_intfdata, usb_submit_urb
5. TODO 4 decode the report and resubmit with GFP_ATOMIC
6. Ctrl-A then C: QEMU monitor. sendkey h, Ctrl-A C back, dmesg | tail

the starter, before TODO 1 (real)

$ insmod sysprog_kbd_starter.ko; echo status $?
status 0
$ dmesg | tail -2
# nothing: no probe, the id_table is empty
$ ls /sys/bus/usb/drivers
hub  sysprog_kbd  usb  usbfs

the finished lab (real)

(qemu) sendkey h
(qemu) sendkey shift-b
$ dmesg | grep report
usb 1-1: report 1: 00 00 0b 00 …  key 0x0b 'h'
usb 1-1: report 2: 00 00 00 00 …  (all keys up)
usb 1-1: report 3: 02 00 00 00 …  (all keys up)
usb 1-1: report 4: 02 00 05 00 …  key 0x05 'b' +shift