On Fri, Oct 23, 2020 at 03:14:20PM +0000, Simon Ser wrote: > On Thursday, October 22, 2020 12:14 PM, Ville Syrjälä > <ville.syrj...@linux.intel.com> wrote: > > > On Wed, Oct 21, 2020 at 08:13:43PM -0700, Randy Dunlap wrote: > > > > > Hi, > > > With linux-next 20201021, when booting up, I am seeing this: > > > [ 0.560896] UBSAN: signed-integer-overflow in > > > ../drivers/gpu/drm/drm_modes.c:765:20 > > > [ 0.560903] 2376000 * 1000 cannot be represented in type 'int' > > > > Dang. Didn't realize these new crazy >8k modes have dotclocks reaching > > almost 6 GHz, which would overflow even u32. I guess we'll switch to > > 64bit maths. Now I wonder how many other places can hit this overflow > > in practice... > > Can you provide an example of a full crazy >8k mode?
These are two extreme cases: /* 216 - 10240x4320@100Hz 64:27 */ { DRM_MODE("10240x4320", DRM_MODE_TYPE_DRIVER, 5940000, 10240, 12432, 12608, 13200, 0, 4320, 4336, 4356, 4500, 0, DRM_MODE_FLAG_PHSYNC | DRM_MODE_FLAG_PVSYNC), .picture_aspect_ratio = HDMI_PICTURE_ASPECT_64_27, }, /* 217 - 10240x4320@120Hz 64:27 */ { DRM_MODE("10240x4320", DRM_MODE_TYPE_DRIVER, 5940000, 10240, 10528, 10704, 11000, 0, 4320, 4336, 4356, 4500, 0, DRM_MODE_FLAG_PHSYNC | DRM_MODE_FLAG_PVSYNC), .picture_aspect_ratio = HDMI_PICTURE_ASPECT_64_27, } > I'm trying to get > a fix for my user-space [1], and I'm wondering if int32_t is enough > after dividing by mode->htotal. > > CC Pekka, just FYI (I think Weston has similar code). > > [1]: https://github.com/swaywm/wlroots/pull/2450 What's with those 1000000LL constants? Are you storing clock in Hz units? -- Ville Syrjälä Intel _______________________________________________ dri-devel mailing list dri-devel@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/dri-devel