在撰寫linux driver時,若需要用到其資料(map(iomap,memmap), interrupt ,memory page, and symbol)
這些都可以用來觀察目系統中,對不同的driver所使用的資源有多少.並且可用來看是否有衝突.
keyword:
udev,procfs,interrupt hook,mapping,memory,symbol
1.註冊device,
無論是用register_chrdev() *1, alloc_chrdev_region(),udev(class_create,class_device and class_device_create)*2
均會在出現在 /proc/devices,用來去建立其device inode
Character devices:
1 mem
4 /dev/vc/0
4 tty
5 /dev/tty
5 /dev/console
5 /dev/ptmx
5 ttyprintk
7 vcs
10 misc
Block devices:
1 ramdisk
259 blkext
7 loop
8 sd
65 sd
66 sd
其中若是以udev,則需額外有/sys/class/driver class/driver name
提供其驅動所需的規則檔等..
pi@raspberrypi ~/test/driver/gpio_io $ sudo ls /sys/class/
bcm2708_vcio dma input iscsi_session mmc_host rtc sound uio vc-sm
bdi gpio iscsi_connection iscsi_transport net scsi_device spidev vc vtconsole
block graphics iscsi_endpoint leds power_supply scsi_disk spi_master vc-cma
bluetooth hidraw iscsi_host mem raw scsi_generic thermal vchiq
bsg i2c-adapter iscsi_iface misc rfkill scsi_host tty vc-mem
2. Interrupt Hook
因在嵌入式系統,會用到許多來自內/外的中斷來進行狀態的轉換及操作.
request_irq(),向kernel 去註冊interrup
CPU0
9437 ARMCTRL 3 BCM2708 Timer Tick
0 ARMCTRL 16 bcm2708_fb dma
4694 ARMCTRL 24 DMA IRQ
0585 ARMCTRL 25 DMA IRQ
7362 ARMCTRL 32 dwc_otg, dwc_otg_pcd, dwc_otg_hcd:usb1
0 ARMCTRL 49 20200000.gpio:bank0
0 ARMCTRL 50 20200000.gpio:bank1
2864 ARMCTRL 65 ARM Mailbox IRQ
2 ARMCTRL 66 VCHIQ doorbell
1 ARMCTRL 75
524 ARMCTRL 83 uart-pl011
4012 ARMCTRL 84 mmc0
usb_fiq
0
3.mapping
又分為io memory mapping and memory mapping.*3
/proc/ioports and /proc/iomem *4
$sudo less /proc/iomem
00000000-1bffffff : System RAM
00008000-0078ebe7 : Kernel code
007e4000-008f27a7 : Kernel data
20000000-20000fff : bcm2708_vcio
20003000-20003fff : bcm2708_systemtimer
20006000-20006fff : bcm2708_usb
20006000-20006fff : dwc_otg
20007000-20007fff : bcm2708_dma.0
20007000-20007fff : bcm2708_dma
20100000-201000ff : bcm2708_powerman.0
20200000-202000b3 : /soc/gpio
20201000-20201fff : dev:f1
20201000-20201fff : uart-pl011
20300000-203000ff : mmc-bcm2835.0
20300000-203000ff : mmc0
20980000-2099ffff : bcm2708_usb
20980000-2099ffff : dwc_otg
4.memory (page)
在kernel中,所使用全域變數等也會在kernel中去檢查.像是cache,及page)*5
slabinfo - version: 2.1
# name <;active_objs> <num_objs> <objsize> <objperslab> <pagesperslab> : tunables <limit> <batchcount> <sharedfactor> : slabdata <active_slabs> <num_slabs> <sharedavail>isofs_inode_cache 0 0 344 23 2 : tunables 0 0 0 : slabdata 0 0 0
udf_inode_cache 0 0 408 10 1 : tunables 0 0 0 : slabdata 0 0 0
nf_conntrack_c082c640 20 80 248 16 1 : tunables 0 0 0 : slabdata 5 5 0
nf_conntrack_expect 0 0 184 22 1 : tunables 0 0 0 : slabdata 0 0 0
cfq_queue 0 0 152 26 1 : tunables 0 0 0 : slabdata 0 0 0
bsg_cmd 0 0 288 14 1 : tunables 0 0 0 : slabdata 0 0 0
mqueue_inode_cache 8 8 512 8 1 : tunables 0 0 0 : slabdata 1 1 0
nat_entry_set 0 0 24 170 1 : tunables 0 0 0 : slabdata 0 0 0
f2fs_inode_cache 0 0 408 10 1 : tunables 0 0 0 : slabdata 0 0 0
nfs_direct_cache 0 0 96 42 1 : tunables 0 0 0 : slabdata 0 0 0
nfs_commit_data 9 9 448 9 1 : tunables 0 0 0 : slabdata 1 1 0
nfs_read_data 42 42 576 14 2 : tunables 0 0 0 : slabdata 3 3 0
nfs_inode_cache 0 0 616 13 2 : tunables 0 0 0 : slabdata 0 0 0
fat_inode_cache 17 20 392 10 1 : tunables 0 0 0 : slabdata 2 2 0
fat_cache 0 0 24 170 1 : tunables 0 0 0 : slabdata 0 0 0
jbd2_revoke_table_s 256 256 16 256 1 : tunables 0 0 0 : slabdata 1 1 0
ext4_inode_cache 22359 22372 584 14 2 : tunables 0 0 0 : slabdata 1598 1598 0
ext4_allocation_context 156 156 104 39 1 : tunables 0 0 0 : slabdata 4 4 0
ext4_io_end 102 204 40 102 1 : tunables 0 0 0 : slabdata 2 2 0
ext4_extent_status 8064 8064 32 128 1 : tunables 0 0 0 : slabdata 63 63 0
configfs_dir_cache 0 0 56 73 1 : tunables 0 0 0 : slabdata 0 0 0
dquot 25 50 160 25 1 : tunables 0 0 0 : slabdata 2 2 0
kioctx 0 0 224 18 1 : tunables 0 0 0 : slabdata 0 0 0
posix_timers_cache 23 23 176 23 1 : tunables 0 0 0 : slabdata 1 1 0
rpc_inode_cache 0 0 352 11 1 : tunables 0 0 0 : slabdata 0 0 0
UNIX 43 45 544 15 2 : tunables 0 0 0 : slabdata 3 3 0
UDP-Lite 0 0 640 12 2 : tunables 0 0 0 : slabdata 0 0 0
RAW 13 13 608 13 2 : tunables 0 0 0 : slabdata 1 1 0
UDP 36 36 640 12 2 : tunables 0 0 0 : slabdata 3 3 0
tw_sock_TCP 25 125 160 25 1 : tunables 0 0 0 : slabdata 5 5 0
TCP 33 72 1344 12 4 : tunables 0 0 0 : slabdata 6 6 0
cachefiles_object_jar 0 0 192 21 1 : tunables 0 0 0 : slabdata 0 0 0
fscache_cookie_jar 85 85 48 85 1 : tunables 0 0 0 : slabdata 1 1 0
eventpoll_pwq 135 306 40 102 1 : tunables 0 0 0 : slabdata 3 3 0
blkdev_queue 32 32 1016 8 2 : tunables 0 0 0 : slabdata 4 4 0
blkdev_requests 29 85 232 17 1 : tunables 0 0 0 : slabdata 5 5 0
biovec-256 10 10 3072 10 8 : tunables 0 0 0 : slabdata 1 1 0
biovec-128 10 50 1536 10 4 : tunables 0 0 0 : slabdata 5 5 0
biovec-64 10 20 768 10 2 : tunables 0 0 0 : slabdata 2 2 0
Node 0, zone Normal 506 77 2 27 7 3 2 0 0 0 2
5.symbol
當使用全域變數時,*6
$sudo less /proc/kallsyms
c0008000 T stext
c0008000 T _text
c0008078 t __create_page_tables
c0008124 t __turn_mmu_on_loc
c0008130 t __enable_mmu
c0008160 t __vet_atags
c00081c0 T do_undefinstr
c00081c0 T _stext
c00081c0 T __exception_text_start
c00083bc T do_DataAbort
c0008464 T do_PrefetchAbort
c000850c T __exception_text_end
c0008510 T asm_do_IRQ
c0008510 T __irqentry_text_start
c0008540 T handle_fiq_as_nmi
c00085cc T __irqentry_text_end
c00085d0 t __do_fixup_smp_on_up
c00085e4 T fixup_smp
c00085fc t __lookup_processor_type
c0008634 t __lookup_processor_type_data
c0008640 t __error_lpae
c0008644 t __error
c0008644 t __error_p
c000864c t run_init_process
c0008684 t try_to_run_init_process
c00086d0 T do_one_initcall
c00088b4 t match_dev_by_uuid
c00088f0 t rootfs_mount
c0008970 T name_to_dev_t
c0008d20 t init_linuxrc
c0008de4 T calibrate_delay
c00093a4 t vfp_emulate_instruction.isra.0
c00093f8 t vfp_raise_sigfpe.isra.1
c0009478 t vfp_enable
c00094cc t vfp_raise_exceptions
c0009628 T VFP_bounce
c0009760 T vfp_sync_hwstate
c00097e8 t vfp_notifier
c0009948 T vfp_flush_hwstate
c00099d0 T vfp_preserve_user_clear_hwstate
c0009a6c T vfp_restore_user_hwstate
c0009af0 T vfp_kmode_exception
*1.should be on linux kernel 2.4.x,not commond for 2.6.x and other
*2.udev
*3.io mapping及memory mapping簡單就是分別為將io視為特殊的位置及存取指令或一則無.
*4.若要使用io/memory mapping時,也需去檢查是否已經有被其它driver申請,否則也會出現衝突.
*5.若由,kmalloc,kfree等為Slab allocator 則為cache為單位.故其實是呼叫kmem_cache_create()'kmem_cache_destory())
而vmalloc(),ioremap()等則是以Buddy System,是以page為單位.
*6:全域變數會在整個驅動之內分享
使用EXPORT_SYMBOL來對外公開
