On Mon, Nov 12, 2012 at 1:27 PM, Russell King - ARM Linux linux@arm.linux.org.uk wrote:
On Fri, Nov 09, 2012 at 03:17:33PM -0600, Rob Clark wrote:
From: Rob Clark rob@ti.com
A new atomic modeset/pageflip ioctl being developed in DRM requires get_user() to work for 64bit types (in addition to just put_user()).
NAK.
(I did write a better email explaining all the ins and outs of why this won't work and why 64-bit get_user isn't possible, but my editor crapped out and lost all that well written message; I don't fancy typing it all out again.)
Nevertheless, int test_ptr(unsigned int **v, unsigned int **p) { return get_user(*v, p); }
produces a warning, and you can't get away from that if you stick 64-bit support into get_user().
Actually, it seems like using 'register typeof(x) __r2 asm("r2");' does avoid that warning..
I don't know if that was the only argument against 64-bit get_user(). But it will at least be inconvenient that get_user() works for 64bit on x86 but not arm..
BR, -R
Sorry, 64-bit get_user() is a no-no.
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