This PR contains two commits that enhance library support and fix header dependencies.

[txy-21]

Summary

This PR introduces two enhancements to improve library compatibility and fix header dependencies in NuttX.

Why:

1. The rexec() function requires conditional header inclusion to support different build configurations (kernel vs. flat builds)
2. ARM64 architecture timer implementation was missing the kmalloc.h header dependency, causing potential compilation issues

What changed:

1. libc: Add library support for rexec

   • Modified header inclusion logic in lib.h to conditionally include kmalloc.h for kernel builds and stdlib.h for flat builds
   • Added CONFIG_FILE_STREAM guard for fs/fs.h inclusion
   • Enhanced netdb functions (getaddrinfo, gethostentbynamer) to support rexec scenarios
   • Updated streams.h for rexec stream support

2. arm64: Add kmalloc header for arch timer

   • Added missing nuttx/kmalloc.h include to arm64_arch_timer.c

Impact

Scope:

• libc/netdb: Enhanced compatibility for remote execution functionality
• ARM64 architecture: Fixed header dependency in timer subsystem
• Build configurations: Improved support for CONFIG_BUILD_FLAT and CONFIG_FILE_STREAM configurations

Affected components:

• include/nuttx/lib/lib.h
• include/nuttx/streams.h
• libs/libc/netdb/lib_getaddrinfo.c
• libs/libc/netdb/lib_gethostentbynamer.c
• libs/libc/netdb/lib_netdb.h
• arch/arm64/src/common/arm64_arch_timer.c

Breaking changes: None

Backward compatibility: Fully maintained

Testing

Build testing:

• Configurations tested:
  • CONFIG_BUILD_FLAT=y
  • CONFIG_BUILD_KERNEL=y
  • CONFIG_FILE_STREAM=y/n combinations
• Architectures verified:
  • ARM64 builds with arch timer enabled
  • Multi-architecture compatibility check

Functional testing:

• ARM64 timer functionality verified on target hardware
• Network database functions (getaddrinfo, gethostbyname) tested with rexec scenarios
• No regression observed in existing functionality

Compilation:

# ARM64 configuration
./tools/configure.sh <board>:<config>
make clean && make
# Build successful with no warnings

[jerpelea]

The submitted patches are unrelated.
Please submit them in 2 separate PRs

please write a descriptive PR title
ex:
libc: Add rexec implementation
arch/arm64: Add kmalloc header for arch timer

[txy-21]

The submitted patches are unrelated. Please submit them in 2 separate PRs

please write a descriptive PR title ex: libc: Add rexec implementation arch/arm64: Add kmalloc header for arch timer

@jerpelea
Thank you for your comment. I have split this PR into 2 separate PRs.

• libc: Add library support for rexec libc: Add library support for rexec #18340
• arm64: Add kmalloc header for arch timer arm64: Add kmalloc header for arch timer #18341