On Fri, Oct 11, 2013 at 10:37:25PM -0400, Pavel Roskin wrote: > Hello! > > I'm running 32-bit Ubuntu 12.04 on the latest x86_64 kernel > (mainline git). I'm using the latest X from the x-edgers PPA > (2.99.904+git20131009.b9ad5b62-0ubuntu0sarvatt~precise). > > The Intel Xorg driver fails with: > > (EE) intel(0): No outputs and no modes. > > Xorg works with the i386 kernel in the same configuration. > > This is my understanding of what is happening. > > sna_output_init() in the userspace driver calls > DRM_IOCTL_MODE_GETCONNECTOR. It sets conn.encoders_ptr to a 32-bit > pointer (an address of enc.encoder_id in the process memory). That > pointer is never converted to a 64-bit pointer. > > drm_mode_getconnector() in the kernel simply calls put_user() on > that pointer to write the encoder IDs. Debug printing shows that > the pointer is indeed a 32-bit value. The encoder ID goes to a > wrong place in the memory. > > Then sna_output_init() calls DRM_IOCTL_MODE_GETENCODER with the > enc.encoder_id that wasn't written to by the kernel, so it's 0. > drm_mode_getencoder() in the kernel returns -EINVAL. > sna_output_init() fails. Xorg assumes there are no valid screens > and exits. > > I believe the error is on the kernel side. The kernel should > convert the pointer. compat_ptr() doesn't convert the value, only > the type. The comment in arch/x86/include/asm/compat.h says: That seems odd as the kernel expects a 32-bit address for the user process here. Can you please attach a dmesg with drm.debug=7 and --enable-debug=full Xorg.0.log? -Chris -- Chris Wilson, Intel Open Source Technology Centre _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx http://lists.freedesktop.org/mailman/listinfo/dri-devel
