On 03/23/2013 09:17 AM, Paul Berry wrote:
Gen7 adds mask bits to the message header for a URB write which allow the write to apply only to certain channels. We don't use this functionality, so to ensure that the entire write always occurs, we emit an OR instruction to set the mask bits.With the advent of geometry shaders, URB writes won't just happen at the end of a thread; they will happen in mid-thread too. Thus, we can no longer rely on channel 0 being enabled, so we need to emit the OR instruction in WE_all mode to ensure that it is executed. --- src/mesa/drivers/dri/i965/brw_eu_emit.c | 1 + 1 file changed, 1 insertion(+) diff --git a/src/mesa/drivers/dri/i965/brw_eu_emit.c b/src/mesa/drivers/dri/i965/brw_eu_emit.c index 992e784..2355626 100644 --- a/src/mesa/drivers/dri/i965/brw_eu_emit.c +++ b/src/mesa/drivers/dri/i965/brw_eu_emit.c @@ -2184,6 +2184,7 @@ void brw_urb_WRITE(struct brw_compile *p, /* Enable Channel Masks in the URB_WRITE_HWORD message header */ brw_push_insn_state(p); brw_set_access_mode(p, BRW_ALIGN_1); + brw_set_mask_control(p, BRW_MASK_DISABLE); brw_OR(p, retype(brw_vec1_reg(BRW_MESSAGE_REGISTER_FILE, msg_reg_nr, 5), BRW_REGISTER_TYPE_UD), retype(brw_vec1_grf(0, 5), BRW_REGISTER_TYPE_UD),
Oh, yeah, that's a good idea. Honestly, it should've been MASK_DISABLE to begin with, I just didn't know what I was doing when I wrote that code, and it happened to work out.
Reviewed-by: Kenneth Graunke <[email protected]> I've always wondered what we -would- use that for. _______________________________________________ mesa-dev mailing list [email protected] http://lists.freedesktop.org/mailman/listinfo/mesa-dev
