Code is valid for gfx9 GPUs excluding gfx94x.
1st level trap handler will use TTMP13[22] to indicate host trap and
TTMP13[21] to indicate stochastic trap.
For each PC sampling method (hosttrap and stochastic), we use a double
buffering mechanism to transfer data between GPU and host.
The GPU will dump data into one buffer while CPU may be reading data
from the other buffer. There are 2 separate signals, one for each
buffer.
When signal != 0, the buffer belongs to the GPU and the GPU can write
to it. Once the buffer has reached the high watermark, the GPU will
set the signal to 0 to wake up the host and so that the host can try
to switch the buffers and read the data.
Co-authored-by: David Yat Sin <David.YatSin@amd.com>
Change-Id: If3eb0913e52fb4788059a71e5feca334612f3d5d
Joseph Greathouse
431a70471e