On Tue, Aug 12, 2008 at 11:44:20PM -0600, Vitaliy Margolen wrote:
While debugging some force-feedback issues ran into an interesting problem. The size of one struct from include/linux differs between 32-bit and 64-bit. That wouldn't be a major problem except that size is the part of the ioctl() request. Which results in EINVAL.
In more details: input.h: #define EVIOCSFF _IOC(_IOC_WRITE, 'E', 0x80, sizeof(struct ff_effect))
The simple test program:
#include <linux/input.h> #include <stdio.h> int main(int argc, char * argv[]) { printf("sizeof(struct ff_effect) = %d EVIOCSFF=%#x\n", sizeof(struct ff_effect), EVIOCSFF);
return 0;}
$ gcc test_size.c -o test_size && ./test_size sizeof(struct ff_effect) = 48 EVIOCSFF=0x40304580 $ gcc -m32 test_size.c -o test_size32 && ./test_size32 sizeof(struct ff_effect) = 44 EVIOCSFF=0x402c4580
The question is what do we do about it? I'm sure there are might be more cases like that.
The kernel is supposed to handle this transparently.
I would report this to the kernel developers, mention "32bit compatibility" or so.
Ciao, Marcus