On Tue, Oct 02, 2018 at 04:49:30PM +0000, Thomas Hellstrom wrote:
Hi, Daniel,
On 10/02/2018 03:35 PM, Daniel Vetter wrote:
The idea behind allowing drivers to override legacy ioctls (instead of using the generic implementations unconditionally) is to handle bugs in old driver-specific userspace. Like e.g. vmw_kms_set_config does, to work around some vmwgfx userspace not clearing its ioctl structs properly.
But you can't use it to augment semantics and put in additional checks, since from a correctly working userspace's pov there should not be any difference in behaviour between the legacy and the atomic paths.
vmwgfx seems to be doing some strange things in its page_flip handlers. Since I'm not an expert of this codebase just wrap some FIXME comments around the potentially problematic code.
We've got proper patches for these. Apparently they got lost in my -next pull request, though.
Yeah I wondered why this one here didn't conflict yet, I can carry it around a bit longer as a memo. -Daniel