[NevynUK]

First part of Phase 4: Mono now starts on the board and runs a managed Hello World, and its output reaches meadow listen; GC stress passes under both the JIT and the interpreter. Blinky is still to do.

Changes

• MonoControl options now reach Mono. meadow_mono_main used to ignore the options that hcom builds from meadow.config.yaml, and Legacy ignores them too. They now go into MONO_ENV_OPTIONS. They can't be passed as arguments, because monovm_execute_assembly puts the assembly first and mono_main() stops reading runtime options there. Tested with --interp and --debug.
• stdout/stderr redirect: CONFIG_HCOM_MONO_STDERR_STDOUT=y, plus two fixes in hcom_stdxxx_redirect.c:
  • POLLHUP spin. The FIFOs were opened O_RDONLY, and NuttX reports POLLHUP on an empty FIFO with no writer. While Mono wasn't running, the read loop spun and starved hcom, so the CLI couldn't connect. They are now opened O_RDWR.
  • Wrong dup2 target. hcom_mono_open_mono_fifo() dup2'd both FIFOs onto fd 1, so stdout arrived labelled stderr and stderr was lost. Legacy has the same bug.
• Runtime pin: points at runtime MergeManagedCode fafd81e8032, which contains Phase 4: NuttX 12 stack bounds and Thumb-2 JIT code alignment runtime#4 (NuttX 12 stack bounds and Thumb-2 JIT code alignment) and Merge pull request #4 from WildernessLabs/peter-rebase-point-2 #5 (Thumb-2 LDR/STR with negative offsets, which fixes --interp). Its tree is the same as the Phase4b head that was tested.

Testing (CCM, 1.99.1.7)

• Managed set on /meadow0:
  • CoreLib built from the runtime (build.sh -subset mono.corelib -arch arm -os linux -c Release /p:FeaturePerfTracing=false)
  • 11 framework assemblies from the 3.0.0 meadow_assemblies package
  • a net11.0 console Meadow.dll
• Results: mono_exec returned: ret=0x00000000 exit_code=42 under the JIT (about 5.8 s), the JIT with --debug, and --interp (about 3.5 s). A breakpoint confirmed that --interp really uses the interpreter.
• meadow listen output: stdout> Hello from Meadow!, stderr> Hello from Meadow on stderr, and stdout> mono_mbedtls_init: OK.
• CLI: connects with Mono disabled and the redirect active, and the CLI commands still work.
• GC stress (a net11.0 app: nursery churn, a retained 65535-node tree, large objects, strings, 3 allocating threads with forced collections, finalizers, weak references), 5 passes each:
  • JIT --debug: 30/30 tests pass, 121 s.
  • --interp: 30/30 tests pass, 229 s. Before runtime#5, the board locked up with SP = 0 in the first test.

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