alignment issue between 32bit userland and 64bit kernel

alignment issue between 32bit userland and 64bit kernel

[Masakazu Mokuno]

	Hi,

While developing the wireless support for PS3, I'd noticed there were alignment
issues if we issued some wireless ioctl from 32bit userland to 64bit
kernel (ppc64 PS3 does have). 

 - IW_EV_LCP_LEN in 32bit userland and 64bit kernel differ
 - offsetof(struct iw_point, length) differ

The former issue could be fixed if we added 'packed' attribute to
iw_event structure, but it would break existing 64bit userland.  I have
no idea to resolve latter issue because the first member of struct
iw_point is a pointer.

Does anyone have idea to fix these issues?
(except compiling all userland apps in 64bit mode...)

The following is the output from a test code on my PS3.

> # cat test.c
> #include <stdio.h>
> #include <netdb.h>
> #include <linux/wireless.h>
> /* packed version */
> struct iw_event_p {
>   __u16         len;
>   __u16         cmd;
>   union iwreq_data      u;
> } __attribute__((packed));
> 
> int main(void)
> {
>   printf("IW_EV_LCP_LEN=%d offset=%d,%d\n",
>          IW_EV_LCP_LEN,
>          offsetof(struct iw_event, u),
>          offsetof(struct iw_event_p, u));
>   printf("iw_event=%d iw_event_p=%d iwreq_data=%d\n",
>          sizeof(struct iw_event),
>          sizeof(struct iw_event_p),
>          sizeof(union iwreq_data));
> 
>   /* --- */
> 
>   printf("iw_point=%d length=%d flags=%d\n",
>          sizeof(struct iw_point),
>          offsetof(struct iw_point, length),
>          offsetof(struct iw_point, flags));
>   return 0;
> }
> # cc -m64 -o test_64 test.c; cc -o test_32  test.c
> # ./test_64
> IW_EV_LCP_LEN=8 offset=8,4
> iw_event=24 iw_event_p=20 iwreq_data=16
> iw_point=16 length=8 flags=10
> # ./test_32
> IW_EV_LCP_LEN=4 offset=4,4
> iw_event=20 iw_event_p=20 iwreq_data=16
> iw_point=8 length=4 flags=6
> # 

regards

--
Masakazu MOKUNO

Re: alignment issue between 32bit userland and 64bit kernel

[Johannes Berg]

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Hi,

> While developing the wireless support for PS3, I'd noticed there were alignment
> issues if we issued some wireless ioctl from 32bit userland to 64bit
> kernel (ppc64 PS3 does have). 
> 
>  - IW_EV_LCP_LEN in 32bit userland and 64bit kernel differ
>  - offsetof(struct iw_point, length) differ

Yeah, we're aware of them.

> The former issue could be fixed if we added 'packed' attribute to
> iw_event structure, but it would break existing 64bit userland.  I have
> no idea to resolve latter issue because the first member of struct
> iw_point is a pointer.
> 
> Does anyone have idea to fix these issues?
> (except compiling all userland apps in 64bit mode...)

Jean wants to fix them in userspace. In fact, if you upgrade your
userspace to the really latest version it *should* work. wpa_supplicant
still doesn't work, nor do most distribution's versions of network
manager because the fixes haven't been backported.

johannes

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Re: alignment issue between 32bit userland and 64bit kernel

[Jean Tourrilhes]

On Mon, Jul 09, 2007 at 02:03:23PM +0200, Johannes Berg wrote:
> Hi,
> 
> > While developing the wireless support for PS3, I'd noticed there were alignment
> > issues if we issued some wireless ioctl from 32bit userland to 64bit
> > kernel (ppc64 PS3 does have). 
> > 
> >  - IW_EV_LCP_LEN in 32bit userland and 64bit kernel differ
> >  - offsetof(struct iw_point, length) differ
> 
> Yeah, we're aware of them.
> 
> > The former issue could be fixed if we added 'packed' attribute to
> > iw_event structure, but it would break existing 64bit userland.  I have
> > no idea to resolve latter issue because the first member of struct
> > iw_point is a pointer.
> > 
> > Does anyone have idea to fix these issues?
> > (except compiling all userland apps in 64bit mode...)
> 
> Jean wants to fix them in userspace. In fact, if you upgrade your
> userspace to the really latest version it *should* work. wpa_supplicant
> still doesn't work, nor do most distribution's versions of network
> manager because the fixes haven't been backported.

	You need :
		Wireless Tools 29-pre20 or later
		network manager 0.6.5 or later
	Distro that have those versions :
		Gentoo 2007.0
		Debian unstable
		Ubuntu Gutsy
		OpenSuSE 10.3a5
	We are getting there...
	The situation with wpa_supplicant is most unfortunate,
fortunately x-supplicant should work properly, as it uses libiw.

> johannes

	Thanks...

	Jean

Re: alignment issue between 32bit userland and 64bit kernel

[Masakazu Mokuno]

	Hi

On Mon, 9 Jul 2007 09:46:32 -0700
Jean Tourrilhes <jt@hpl.hp.com> wrote:

> > Jean wants to fix them in userspace. In fact, if you upgrade your
> > userspace to the really latest version it *should* work. wpa_supplicant
> > still doesn't work, nor do most distribution's versions of network
> > manager because the fixes haven't been backported.
> 
> 	You need :
> 		Wireless Tools 29-pre20 or later

I downloaded Wireless Tools 29 pre22 and its iwlist worked fine on my
PS3.

Thank you.

--
Masakazu MOKUNO