1.. _skiboot-6.0.6:
2
3=============
4skiboot-6.0.6
5=============
6
7skiboot 6.0.6 was released on Thursday July 19th, 2018. It replaces
8:ref:`skiboot-6.0.5` as the current stable release in the 6.0.x series.
9
10It is recommended that 6.0.5 be used instead of any previous 6.0.x version,
11especially in the case where NVLINK2 GPUs and/or Mellanox CX5 adapters are
12being used.
13
14Over :ref:`skiboot-6.0.5` we have several important performance related bug
15fixes and one stability bug fix:
16
17- phb4/CAPI: Reallocate PEC2 DMA-Read engines to improve GPU-Direct bandwidth
18
19  We reallocate additional 16/8 DMA-Read engines allocated to stack0/1
20  on PEC2 respectively. This is needed to improve bandwidth available to
21  the Mellanox CX5 adapter when trying to read GPU memory (GPU-Direct).
22
23  If kernel cxl driver indicates a request to allocate maximum possible
24  DMA read engines when calling enable_capi_mode() and card is attached
25  to PEC2/stack0 slot then we assume its a Mellanox CX5 adapter. We then
26  allocate additional 16/8 extra DMA read engines to stack0 and stack1
27  respectively on PEC2. This is done by populating the
28  XPEC_PCI_PRDSTKOVR and XPEC_NEST_READ_STACK_OVERRIDE as suggested by
29  the h/w team.
30- phb4: Disable nodal scoped DMA accesses when PB pump mode is enabled
31
32  By default when a PCIe device issues a read request via the PHB it is first
33  issued with nodal scope. When accessing GPU memory the NPU does not know at the
34  time of response if the requested memory page is off node or not. Therefore
35  every read of GPU memory by a PHB is retried with larger scope which introduces
36  bandwidth and latency issues.
37
38  On smaller boxes which have pump mode enabled nodal and group scoped reads are
39  treated the same and both types of request are broadcast to one chip. Therefore
40  we can avoid the retry by disabling nodal scope on the PHB for these boxes. On
41  larger boxes nodal (single chip) and group (multiple chip) scoped reads are
42  treated differently. Therefore we avoid disabling nodal scope on large boxes
43  which have pump mode disabled to avoid all PHB requests being broadcast to
44  multiple chips.
45- npu2/hw-procedures: Enable parity and credit overflow checks
46
47  Enable these error checking features by setting the appropriate bits in
48  our one-off initialization of each "NTL Misc Config 2" register.
49
50  The exception is NDL RX parity checking, which should be disabled during
51  the link training procedures.
52