Re: What to do when size of the struct differs on 32 and 64 bit?

[Anssi Hannula]

Marcus Meissner wrote:
 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.

Just for the record, it has been fixed for 2.6.27:
http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commitdiff;h=f2278f31d6feb9036eaa79f2e8abcce850420abd

-- 
Anssi Hannula

Re: What to do when size of the struct differs on 32 and 64 bit?

[H. Verbeet]

2008/8/13 Vitaliy Margolen [EMAIL PROTECTED]:
 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.

Maybe I misunderstand the issue, but doesn't Wine currently always get
compiled for 32-bit? (Iow, we always get the 32-bit version of the
structure)

Re: What to do when size of the struct differs on 32 and 64 bit?

[Michael Karcher]

Am Mittwoch, den 13.08.2008, 09:07 +0200 schrieb H. Verbeet:
 Maybe I misunderstand the issue, but doesn't Wine currently always get
 compiled for 32-bit? (Iow, we always get the 32-bit version of the
 structure)
Yes, but if wine runs on a 64 bit kernel, the kernel does not handle the
request, as it only recognizes the 64 bit request, if I understood
Vitaliy correct. I consider that a kernel bug.

Regards,
  Michael Karcher

Re: What to do when size of the struct differs on 32 and 64 bit?

[H. Verbeet]

2008/8/13 Michael Karcher [EMAIL PROTECTED]:
 Yes, but if wine runs on a 64 bit kernel, the kernel does not handle the
 request, as it only recognizes the 64 bit request, if I understood
 Vitaliy correct. I consider that a kernel bug.

I'd say so, yeah.

Re: What to do when size of the struct differs on 32 and 64 bit?

[Dmitry Timoshkov]

Vitaliy Margolen [EMAIL PROTECTED] 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.

64-bit kernel should take care of translating the parameters between native
64-bit and emulated 32-bit modes. If that's not the case that's a kernel
bug, and should be reported appropriately.

-- 
Dmitry.

Re: What to do when size of the struct differs on 32 and 64 bit?

[Marcus Meissner]

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

What to do when size of the struct differs on 32 and 64 bit?

[Vitaliy Margolen]

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.

Vitaliy