Messages in this thread | | | Date | Tue, 25 Jan 2011 00:04:10 -0500 | From | Mark Lord <> | Subject | Re: 2.6.36/2.6.37: broken compatibility with userspace input-utils ? |
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On 11-01-24 11:55 PM, Dmitry Torokhov wrote: > On Mon, Jan 24, 2011 at 11:37:06PM -0500, Mark Lord wrote: .. >> This results in (map->size==10) for 2.6.36+ (wrong), >> and a much larger map->size for 2.6.35 and earlier. >> >> So perhaps EVIOCGKEYCODE has changed? >> > > So the utility expects that all devices have flat scancode space and > driver might have changed so it does not recognize scancode 10 as valid > scancode anymore. > > The options are: > > 1. Convert to EVIOCGKEYCODE2 > 2. Ignore errors from EVIOCGKEYCODE and go through all 65536 iterations.
or 3. Revert/fix the in-kernel regression.
The EVIOCGKEYCODE ioctl is supposed to return KEY_RESERVED for unmapped (but value) keycodes, and only return -EINVAL when the keycode itself is out of range.
That's how it worked in all kernels prior to 2.6.36, and now it is broken. It now returns -EINVAL for any unmapped keycode, even though keycodes higher than that still have mappings.
This is a bug, a regression, and breaks userspace. I haven't identified *where* in the kernel the breakage happened, though.. that code confuses me. :)
Thanks.
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