RFR: 8262491: AArch64: CPU description should contain compatible board list

[Yasumasa Suenaga]

HotSpot generates CPU description when it is started. We can see it `jdk.CPUInformation` JFR event as below:

$ jfr print --events jdk.CPUInformation raspi4.jfr
jdk.CPUInformation {
  startTime = 22:57:13.521
  cpu = "AArch64"
  description = "AArch64 0x41:0x0:0xd08:3, simd, crc"
  sockets = 4
  cores = 4
  hwThreads = 4
}

`description` contains "AArch64", it is fixed value, we cannot guess the process was run on what machine (SoC).

In Linux, we can use `compatible`property in device tree to guess the machine. The 'compatible' property contains a sorted list of strings starting with the exact name of the machine, followed by an optional list of boards it is compatible with sorted from most compatible to least.

After this change, we can get the description as below:

jdk.CPUInformation {
  startTime = 00:32:49.767
  cpu = "AArch64"
  description = "raspberrypi,4-model-b brcm,bcm2711 0x41:0x0:0xd08:3, simd, crc"
  sockets = 4
  cores = 4
  hwThreads = 4
}

In Linux on AMD64, we can see as following, then we can guess the CPU model from it. The same should do for AArch64.

jdk.CPUInformation {
  startTime = 17:28:03.907
  cpu = "AMD (null) (HT) SSE SSE2 SSE3 SSSE3 SSE4.1 SSE4.2 SSE4A AMD64"
  description = "Brand: AMD Ryzen 3 3300X 4-Core Processor , Vendor: AuthenticAMD
Family: <unknown> (0x17), Model: <unknown> (0x71), Stepping: 0x0
Ext. family: 0x8, Ext. model: 0x7, Type: 0x0, Signature: 0x00870f10
Features: ebx: 0x01020800, ecx: 0xfed83203, edx: 0x178bfbff
Ext. features: eax: 0x00870f10, ebx: 0x20000000, ecx: 0x004003f3, edx: 0x2fd3fbff
Supports: On-Chip FPU, Virtual Mode Extensions, Debugging Extensions, Page Size Extensions, Time Stamp Counter, Model Specific Registers, Physical Address Extension, Machine Check Exceptions, CMPXCHG8B Instruction, On-Chip APIC, Fast System Call, Memory Type Range Registers, Page Global Enable, Machine Check Architecture, Conditional Mov Instruction, Page Attribute Table, 36-bit Page Size Extension, CLFLUSH Instruction, Intel Architecture MMX Technology, Fast Float Point Save and Restore, Streaming SIMD extensions, Streaming SIMD extensions 2, Hyper Threading, Streaming SIMD Extensions 3, PCLMULQDQ, Supplemental Streaming SIMD Extensions 3, Fused Multiply-Add, CMPXCHG16B, Streaming SIMD extensions 4.1, Streaming SIMD extensions 4.2, MOVBE, Popcount instruction, AESNI, XSAVE, OSXSAVE, AVX, F16C, LAHF/SAHF instruction support, Core multi-processor leagacy mode, Advanced Bit Manipulations: LZCNT, SSE4A: MOVNTSS, MOVNTSD, EXTRQ, INSERTQ, Misaligned SSE mode, SYSCALL/SYSRET, Execute Disab
 le Bit, RDTSCP, Intel 64 Architecture"
  sockets = 1
  cores = 2
  hwThreads = 2
}

-------------

Commit messages:
 - 8262491: AArch64: CPU description should contain compatible board list

Changes: https://git.openjdk.java.net/jdk/pull/2759/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=2759&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8262491
  Stats: 23 lines in 1 file changed: 21 ins; 0 del; 2 mod
  Patch: https://git.openjdk.java.net/jdk/pull/2759.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/2759/head:pull/2759

PR: https://git.openjdk.java.net/jdk/pull/2759