Re: DRM and permanent SAREA

[Thomas Hellström]

Hi. Jon Smirl wrote: On 6/21/05, Jon Smirl <[EMAIL PROTECTED]> wrote: Second choice would be to make a new map type, DRM_VSHM. The specific driver would initmap the needed space at load time. The code implementing it would be identical to DRM_SHM, you just need another map type defined so that you can tell them apart. This scheme does not require anyone to be root and does not have a kernel DOS hole. So back to the original topic. I'll add a new map type DRM_VSHM. When initializing, the chip specific driver needs to do something like this: if ((ret = drm_initmap(dev, 0, video_size, 0, _DRM_VSHM, 0))) goto err_g1; The map needs to be created in the driver. Opening it up to a normal user is a DOS hole where the kernel can be run out of memory. Use getmap to find the map from user space. Really what is needed is a shmget thingy that returns a handle to a map  which is only mappable by  authorized clients. If I understand your solution above, there would be only one extra shared map, and it needs to be looked up from user space, which would be equivalent to allocating a twice as large primary sarea and reserve half of it to applications other than OpenGL, and is hence not needed. Why not have a thing similar to drmAddMap doing this (but not root-only)? With proper checks I can't see why that would be a bigger security hole than shmget? /Thomas