linux kernel version: 4.4.38
hardware : exynos4412-tiny4412
起因：我向调试开发板上的网络设备驱动，需要更新kernel，更新后发现开发板无法启动，log如下：
1 [ 2.123373] usb4604 usb-hub: switched to HUB mode 2 [ 2.123422] usb4604 usb-hub: usb4604_probe: probed in hub mode 3 [ 2.125274] mousedev: PS/2 mouse device common for all mice 4 [ 2.131205] edt_ft5x06 1-0038: touchscreen probe failed 5 [ 2.136329] touchscreen-1wire initialized 6 [ 2.139793] ts-backlight initialized 7 [ 2.143515] tiny4412_1wire 139d0000.tiny4412_1wire: can't request region for resource [mem 0x139d0000-0x139d0fff] 8 [ 2.153639] setup_irq: ret = 0 9 [ 2.156670] timer_for_1wire clock = 100000000 10 [ 2.160989] Unable to handle kernel paging request at virtual address fffffff0 11 [ 2.168190] pgd = c0004000 12 [ 2.170878] [fffffff0] *pgd=6fffd861, *pte=00000000, *ppte=00000000 13 [ 2.177121] Internal error: Oops: 37 [#1] PREEMPT SMP ARM 14 [ 2.182500] Modules linked in: 15 [ 2.185541] CPU: 0 PID: 1 Comm: swapper/0 Not tainted 4.4.38-tiny4412 #14 16 [ 2.192308] Hardware name: SAMSUNG EXYNOS (Flattened Device Tree) 17 [ 2.198385] task: ef078000 ti: ef080000 task.ti: ef080000 18 [ 2.203769] PC is at init_timer_for_1wire+0x50/0x134 19 [ 2.208714] LR is at init_timer_for_1wire+0x4c/0x134 20 [ 2.213662] pc : [<c0304ff0>] lr : [<c0304fec>] psr: 60000013 21 [ 2.213662] sp : ef081e50 ip : 00000001 fp : 00000000 22 [ 2.225118] r10: c06bd848 r9 : 0000009f r8 : c07427ec 23 [ 2.230327] r7 : ef385810 r6 : 05f5e100 r5 : fffffff0 r4 : c07427ec 24 [ 2.236837] r3 : 00000000 r2 : 00000000 r1 : 00000002 r0 : 00000021 25 [ 2.243348] Flags: nZCv IRQs on FIQs on Mode SVC_32 ISA ARM Segment none 26 [ 2.250465] Control: 10c5387d Table: 4000404a DAC: 00000051 27 [ 2.256193] Process swapper/0 (pid: 1, stack limit = 0xef080210) 28 [ 2.262182] Stack: (0xef081e50 to 0xef082000) 29 [ 2.266524] 1e40: 00000000 c07427ec ef385800 ef385810 30 [ 2.274684] 1e60: c07427ec c030591c c0741ff4 ef385810 c06f102c fffffdfb 00000000 c027b83c 31 [ 2.282843] 1e80: c0741ff4 ef385810 c06f102c 00000000 00000000 c0279f7c ef385810 c06f102c 32 [ 2.291002] 1ea0: ef385844 c06edc38 00000000 c027a0fc 00000000 c06f102c c027a070 c0278424
13行：提示internal error
10行：不能处理虚拟地址，大概是非法内存访问，
7行：不能访问资源范围
于是我去内核源码里搜索tiny4412_1wire关键字，发现
1 moxa@moxa-ThinkPad-X240:~/linux/github/tiny4412/linux-4.4.38-for-tiny4412$ find . -type f -name "*.c" | xargs grep "Unable to handle kernel paging request at virtual address" 2 ./arch/sparc/mm/fault_32.c: printk(KERN_ALERT "Unable to handle kernel paging request at virtual address %08lx\n", 3 moxa@moxa-ThinkPad-X240:~/linux/github/tiny4412/linux-4.4.38-for-tiny4412$ find . -type f -name "*.c" | xargs grep "timer_for_1wire" ./drivers/input/touchscreen/tiny4412_1wire_host.c:static int init_timer_for_1wire(struct device *dev) 4 ./drivers/input/touchscreen/tiny4412_1wire_host.c: printk(KERN_ALERT"timer_for_1wire clock = %ld\n", pclk); 5 ./drivers/input/touchscreen/tiny4412_1wire_host.c:static inline void stop_timer_for_1wire(void) 6 ./drivers/input/touchscreen/tiny4412_1wire_host.c:static irqreturn_t timer_for_1wire_interrupt(int irq, void *dev_id) 7 ./drivers/input/touchscreen/tiny4412_1wire_host.c: stop_timer_for_1wire(); 8 ./drivers/input/touchscreen/tiny4412_1wire_host.c: stop_timer_for_1wire(); 9 ./drivers/input/touchscreen/tiny4412_1wire_host.c:static struct irqaction timer_for_1wire_irq = { 10 ./drivers/input/touchscreen/tiny4412_1wire_host.c: .handler = timer_for_1wire_interrupt, 11 ./drivers/input/touchscreen/tiny4412_1wire_host.c: .dev_id = &timer_for_1wire_irq, 12 ./drivers/input/touchscreen/tiny4412_1wire_host.c: ret = setup_irq(irq_timer3, &timer_for_1wire_irq); 13 ./drivers/input/touchscreen/tiny4412_1wire_host.c: ret = init_timer_for_1wire(dev); 14 ./drivers/input/touchscreen/tiny4412_1wire_host.c: free_irq(irq_timer3, &timer_for_1wire_irq); 15 ./drivers/input/touchscreen/tiny4412_1wire_host.c: ret = init_timer_for_1wire(dev);
然后我猜测这与input设备有关，于是make menuconfig查看touhscreen是否又被编译，
Device Drivers --->
Input device support --->
[*] Touchscreens --->
果然touchscreens被编译了，但是我的触摸屏没有接。
于是取消此编译选项，重新编译，开发成功启动~