OVERVIEW OF CORTEX-A17
- Cortex-A17 architecture
- Organization of a SoC based on Cortex-A17
- AMBA4 coherent interconnect capabilities
- Inner Shareable vs Outer Shareable attribute
- I/O MMU
- 64-Byte cacheline size, integrated L2 cache
- VFPv4 and SIMDv2
- Highlighting differences between Cortex-A9 and Cortex-A17
INSTRUCTION PIPELINE
- Global organization, dual issue capability
- Fetch / decode / rename / dispatch stages
- Loop mode
- Execution clusters
- Out-of-order execution
- Branch accelerators
INTRODUCTION TO HYPERVISOR STATE
- Processor privilege levels state machine, user, guest OS, hypervisor
- Detailing the various operation modes (Bare-Metal, Hypervisor kernel and user task, Hypervisor with Guest partition)
- Asymmetric approach, no support for Virtualization of Secure state functionality
- SVC, HVC and SMC instructions
- Objective of the Hypervisor
- Hypervisor related instructions and registers
- List of registers that have to be saved / restored to be able to suspend / resume a guest partition
- Accessing banked registers or any Non-Secure mode while running in Hypervisor mode
EXCEPTION MECHANISM
- Hypervisor vector table
- Utilization of Vector #5 to trap Guest partition events
- System Call into Hypervisor mode
- Asynchronous exceptions
- Virtual Interrupt and Abort bits control, IRQ, FIQ, external abort routing control
- Hypervisor exception return
- Taking exceptions into Hypervisor mode
GENERIC INTERRUPT CONTROLLER (GICv2)
- Integration in a SoC based on Cortex-A17 and Cortex-A7
- Highlighting the new features with regard to Cortex-A9
- Steering interrupts to guest OS or Hypervisor
- Virtual CPU interface
- Split EOI functionality
- Deactivating an interrupt source from the Virtual CPU interface
- Front-end interface accessed by the Guest Kernel
- Back-end interface accessed by the Hypervisor
VIRTUALIZATION EXTENSIONS
- New Intermediate Physical Address, 2-stage address translation
- Memory translation system
- Memory management when running in hypervisor mode
- Virtual Machine Identification
- Exposing the MMU to Other Masters, IO MMU
- Emulation support, trapping load and store and executing them in Hypervisor state
- Second-stage access permissions and attributes
LARGE PHYSICAL ADDRESS EXTENSIONS SPECIFICATION (LPAE)
- Need to introduce support for a second stage of translation as part of the Virtualization Extensions
- New 3-level translation
- Level-1 table descriptor format
- Level-2 table descriptor format
- Attribute and Permission fields in the translation tables
- Improving the caching of translation entries by providing contiguous hints
- complete set of cache allocation hints
- Handling of the ASID in the LPAE
- New cache and TLB maintenance operations
MMU IMPLEMENTATION
- TLB organization, L1-TLB, L2-TLB
- TLB match process
- Coherent table walk
- Determining the exact cause of aborts through status registers
- Behavior when MMU is disabled
OS SUPPORT – SYNCHRONIZATION OVERVIEW
- Inter-Processor Interrupts
- Barriers
- Cluster ID
- Exclusive access monitor, implementing Boolean semaphores
- Global Monitor
- Spin-lock implementation
- Using events
- Indicating the effect of Multi Core on debug interfaces
LEVEL ONE SUBSYSTEM
- Physically Indexed Physically Tagged caches
- Pseudo LRU replacement algorithm
- Speculative accesses
- Hit Under Miss, Miss under Miss
- Write streaming threshold definition
- L1 cache hardware prefetch
- MOESI data cacheline states
LEVEL TWO SUBSYSTEM
- Cache organization
- Optional ECC protection
- L2 cache hardware flush
- ACE master interface
- ACMP master interface
- ACP slave interface
- By means of sequences involving a multi-core Cortex-A17 and external masters, understanding how snoop requests can be used to maintain coherency of data between caches and memory
GENERIC TIMER
- ARM generic 64-bit timers for each processor
- Virtual time vs Physical time
- Effect of virtualization on these timers
- Event stream purpose
- Kernel event stream generation
- Hypervisor event stream generation
- Gray count timer distribution scheme
PERFORMANCE MONITORING VIRTUALIZATION EXTENSIONS
- Hypervisor performance monitoring
- Guest OS performance monitoring
- Lazy switching of PMU state by a hypervisor
- Reducing the number of counters available to a Guest OS
- Fully virtualizing the PMU identity registers
AMBA4
- AXI-4
- Quality of Service signaling
- Updated meaning of Read Allocate and Write Allocate
- Transaction buffering
- AXI-4 stream protocol
- Byte types, data, position, null
- Byte stream
- Sparse stream
- Data merging, packing, and width conversion
- AXI-4 lite
- Burst length of 1
- No exclusive access support
- AXI Coherency Extension (ACE)
- Shareability domains
- Coherency model, cache states
- Additional channel signals
- New channels, snoop address, snoop response, snoop data
- Studying through sequences how a load request and a store request will be handled whenever they are marked as outer shareable requests
- Using ReadUnique, CleanUnique and MakeUnique requests
- Distributed Virtual Memory (DVM)
- DVM synchronization message
- Selecting the coherency state machine: MESI or MOESI according to the capabilities of the interconnect
- Snoop filtering
- Exported barriers
- DMB / DSB inner shareable, outer shareable or system
HARDWARE IMPLEMENTATION
- Clock domains
- Resets, power-on reset timing diagram
- Valid reset combinations
- Power domains
- Power-on reset sequence, soft reset sequence
- Power management, processor and L2 state retention
- Maintaining coherency while CPUs are in standby state
- Interface to the Power Management Unit
- Powering down a CPU
- External debug over power down
CCI-400 CACHE COHERENT INTERCONNECT
- AMBA 4 snoop request transport
- Snoop connectivity and control
- Connecting 2 CPUs through CCI, managing coherency domains
- Example of Cortex-A7 dual core and Cortex-A17 dual core
CORESIGHT DEBUG
- Program Trace Macrocell
- Cross Trigger Interface and Cross Trigger Matrix for multi-processor debugging
- Adding Virtual Machine ID in the criterion used to set a breakpoint / watchpoint
- Tracking VMID change in trace output
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