diff options
| -rw-r--r-- | src/mesa/drivers/dri/i965/intel_screen.c | 97 |
1 files changed, 97 insertions, 0 deletions
diff --git a/src/mesa/drivers/dri/i965/intel_screen.c b/src/mesa/drivers/dri/i965/intel_screen.c index 2d8e007e79d..17e5a4692e5 100644 --- a/src/mesa/drivers/dri/i965/intel_screen.c +++ b/src/mesa/drivers/dri/i965/intel_screen.c @@ -1748,6 +1748,103 @@ __DRIconfig **intelInitScreen2(__DRIscreen *dri_screen) screen->subslice_total = 1 << (devinfo->gt - 1); } + /* Gen7-7.5 kernel requirements / command parser saga: + * + * - pre-v3.16: + * Haswell and Baytrail cannot use any privileged batchbuffer features. + * + * Ivybridge has aliasing PPGTT on by default, which accidentally marks + * all batches secure, allowing them to use any feature with no checking. + * This is effectively equivalent to a command parser version of + * \infinity - everything is possible. + * + * The command parser does not exist, and querying the version will + * return -EINVAL. + * + * - v3.16: + * The kernel enables the command parser by default, for systems with + * aliasing PPGTT enabled (Ivybridge and Haswell). However, the + * hardware checker is still enabled, so Haswell and Baytrail cannot + * do anything. + * + * Ivybridge goes from "everything is possible" to "only what the + * command parser allows" (if the user boots with i915.cmd_parser=0, + * then everything is possible again). We can only safely use features + * allowed by the supported command parser version. + * + * Annoyingly, I915_PARAM_CMD_PARSER_VERSION reports the static version + * implemented by the kernel, even if it's turned off. So, checking + * for version > 0 does not mean that you can write registers. We have + * to try it and see. The version does, however, indicate the age of + * the kernel. + * + * Instead of matching the hardware checker's behavior of converting + * privileged commands to MI_NOOP, it makes execbuf2 start returning + * -EINVAL, making it dangerous to try and use privileged features. + * + * Effective command parser versions: + * - Haswell: 0 (reporting 1, writes don't work) + * - Baytrail: 0 (reporting 1, writes don't work) + * - Ivybridge: 1 (enabled) or infinite (disabled) + * + * - v3.17: + * Baytrail aliasing PPGTT is enabled, making it like Ivybridge: + * effectively version 1 (enabled) or infinite (disabled). + * + * - v3.19: f1f55cc0556031c8ee3fe99dae7251e78b9b653b + * Command parser v2 supports predicate writes. + * + * - Haswell: 0 (reporting 1, writes don't work) + * - Baytrail: 2 (enabled) or infinite (disabled) + * - Ivybridge: 2 (enabled) or infinite (disabled) + * + * So version >= 2 is enough to know that Ivybridge and Baytrail + * will work. Haswell still can't do anything. + * + * - v4.0: Version 3 happened. Largely not relevant. + * + * - v4.1: 6702cf16e0ba8b0129f5aa1b6609d4e9c70bc13b + * L3 config registers are properly saved and restored as part + * of the hardware context. We can approximately detect this point + * in time by checking if I915_PARAM_REVISION is recognized - it + * landed in a later commit, but in the same release cycle. + * + * - v4.2: 245054a1fe33c06ad233e0d58a27ec7b64db9284 + * Command parser finally gains secure batch promotion. On Haswell, + * the hardware checker gets disabled, which finally allows it to do + * privileged commands. + * + * I915_PARAM_CMD_PARSER_VERSION reports 3. Effective versions: + * - Haswell: 3 (enabled) or 0 (disabled) + * - Baytrail: 3 (enabled) or infinite (disabled) + * - Ivybridge: 3 (enabled) or infinite (disabled) + * + * Unfortunately, detecting this point in time is tricky, because + * no version bump happened when this important change occurred. + * On Haswell, if we can write any register, then the kernel is at + * least this new, and we can start trusting the version number. + * + * - v4.4: 2bbe6bbb0dc94fd4ce287bdac9e1bd184e23057b and + * Command parser reaches version 4, allowing access to Haswell + * atomic scratch and chicken3 registers. If version >= 4, we know + * the kernel is new enough to support privileged features on all + * hardware. However, the user might have disabled it...and the + * kernel will still report version 4. So we still have to guess + * and check. + * + * - v4.4: 7b9748cb513a6bef4af87b79f0da3ff7e8b56cd8 + * Command parser v5 whitelists indirect compute shader dispatch + * registers, needed for OpenGL 4.3 and later. + * + * - v4.8: + * Command parser v7 lets us use MI_MATH on Haswell. + * + * Additionally, the kernel begins reporting version 0 when + * the command parser is disabled, allowing us to skip the + * guess-and-check step on Haswell. Unfortunately, this also + * means that we can no longer use it as an indicator of the + * age of the kernel. + */ if (intel_detect_pipelined_so(screen)) screen->kernel_features |= KERNEL_ALLOWS_SOL_OFFSET_WRITES; |