Messages in this thread | | | Date | Thu, 6 Jan 2005 11:35:20 -0800 | From | Greg KH <> | Subject | Re: [PATCH] macros to detect existance of unlocked_ioctl and ioctl_compat |
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On Thu, Jan 06, 2005 at 06:53:42PM +0100, Andi Kleen wrote: > [cc list trimmed] > > On Thu, Jan 06, 2005 at 06:26:13PM +0100, Petr Vandrovec wrote: > > > Why are you issuing 64bit ioctls from 32bit applications? > > > > There are three reasons (main reason is that vmware is 32bit app, but it is how > > things are currently laid out; even if there will be 64bit app, 32bit versions are > > already in use and people wants to use them on 64bit kernels): > > > > * USB. usbfs API is written in a way which does not allow you to safely wrap > > it in "generic" 32->64 layer, and attempts to do it in non-generic way in usbfs > > code itself did not look feasible year ago. Even on current 64bit kernels it is not > > possible to issue raw USB operations from 32bit apps, and I do not believe that > > it is going to change - after all, just issuing ioctl through 64bit path from application > > which is aware of 64bit kernel is quite simple, much simpler than any attempt to > > make kernel dual-interface. > > Agree that's a problem. We just need an alternative interface here > or I try to come up with an x86-64 specific hack (I think it's possible > to do the compatibility x86-64 specific, just not in compat code for > all architectures who have truly separated user/kernel address spaces) > > I hope the USB people will eventually add a better interface here. > Greg?
Yes, we've been talking about a usbfs2 for a long time now, but no one has stepped up and done the work. It would look a lot like gadgetfs, which only has a limited number of ioctls needed for its operation.
But I don't see where the problem is unique to usbfs here, don't we properly use the 32->64bit ioctl conversion code to solve this kind of issue? Are we using it incorrectly?
thanks,
greg k-h - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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