交叉编译ARM GCC5-正确使用memcpy

Question

I am trying to compile a kernel (uImage) for the S805/S812 SoC from amlogic. I have managed to solve all compilation error except for one, probably because my knowledge of c++ and compilers don't reach far enough. Let me explain the problem, which exist in a file phydev.c :

The line giving the error is :

memcpy(&phydev->name, &dev_para->name, MAX_DEVICE_NAME_LEN*sizeof(char));

These are the (cross)compiler errors:

drivers/amlogic/../../../hardware/amlogic/nand/amlnf/dev/phydev.c: In function ‘amlnand_phydev_init’:

drivers/amlogic/../../../hardware/amlogic/nand/amlnf/dev/phydev.c:1114:10: error: passing argument 1 of ‘memcpy’ discards ‘const’ qualifier from pointer target type [-Werror=discarded-array-qualifiers]

   memcpy(&phydev->name, &dev_para->name, MAX_DEVICE_NAME_LEN*sizeof(char));
          ^
In file included from include/linux/string.h:17:0,
                 from include/linux/dynamic_debug.h:111,
                 from include/linux/kernel.h:14,
                 from include/linux/cache.h:4,
                 from include/linux/time.h:4,
                 from include/linux/stat.h:18,
                 from include/linux/module.h:10,
                 from drivers/amlogic/../../../hardware/amlogic/nand/amlnf/dev/../include/../include/amlnf_type.h:18,
                 from drivers/amlogic/../../../hardware/amlogic/nand/amlnf/dev/../include/../include/amlnf_dev.h:4,
                 from drivers/amlogic/../../../hardware/amlogic/nand/amlnf/dev/../include/phynand.h:4,
                 from drivers/amlogic/../../../hardware/amlogic/nand/amlnf/dev/phydev.c:14:
/root/Downloads/Beelink3/arm-src-kernel-2015-01-15-321cfb5a46/arch/arm/include/asm/string.h:16:15:
 note: expected ‘void *’ but argument is of type ‘const char (*)[16]’

 extern void * memcpy(void *, const void *, __kernel_size_t);
               ^

I have been trying to figure this out for several days, also trying direct assignment (which obviously doesn't work on arrays), using strcpy instead and so on, but this only yields more errors and I can't find the exact root cause. I think I need some kind of cast or intermediate constant void ptr but I have no clue how to fix this.

Could anyone be as kind as to give me advice on this and how to solve it. The memcpy function is defined in arch/arm/include/asm/string.h But it did not seem a good idea messing with this file.

Many thanks,

Wim

Answer 1

Indeed someone had been smart enough to : Struct phydev { const char* name; ...

Removed the const and all was fine (at least the memcpy line. But I could use strcpy or strdup or whatever. It was trying to write to a constant.

After debugging trough all of the other errors I was able to make the U-Boot Image. Haven't tested it yet.

Also, made a lot of functions static instead of copying used static variables into local attributes. Don't know what it's gonna do... (probably crash with some segmentation fault or something:-).

I'll have to wait for my ttl usb adapter now...

Unless anyone know where to find an adb driver for this thing and it supports fw_setenv or something....

Guess it will be pressing the space bar on tty1 once the ttl adapter arrives.

Thanks guys for all your help. If I manage to get Ubuntu on this box I'll post a blog about it :-)

Cheers & thanks

Wim