Add AIX platform-support doc

Author: ecnelises

src/doc/rustc/src/SUMMARY.md

@@ -41,6 +41,7 @@
     - [mipsel-sony-psx](platform-support/mipsel-sony-psx.md)
     - [mipsisa\*r6\*-unknown-linux-gnu\*](platform-support/mips-release-6.md)
     - [nvptx64-nvidia-cuda](platform-support/nvptx64-nvidia-cuda.md)
+    - [powerpc64-ibm-aix](platform-support/aix.md)
     - [riscv32imac-unknown-xous-elf](platform-support/riscv32imac-unknown-xous-elf.md)
     - [sparc-unknown-none-elf](./platform-support/sparc-unknown-none-elf.md)
     - [*-pc-windows-gnullvm](platform-support/pc-windows-gnullvm.md)

src/doc/rustc/src/platform-support.md

@@ -310,7 +310,7 @@ target | std | host | notes
 `powerpc64-wrs-vxworks` | ? |  |
 `powerpc64le-unknown-linux-musl` | ? |  |
 [`powerpc64-unknown-openbsd`](platform-support/openbsd.md) | ✓ | ✓ | OpenBSD/powerpc64
-`powerpc64-ibm-aix` | ? |  | 64-bit AIX (7.2 and newer)
+[`powerpc64-ibm-aix`](platform-support/aix.md) | ? |  | 64-bit AIX (7.2 and newer)
 `riscv32gc-unknown-linux-gnu` |   |   | RISC-V Linux (kernel 5.4, glibc 2.33)
 `riscv32gc-unknown-linux-musl` |   |   | RISC-V Linux (kernel 5.4, musl + RISCV32 support patches)
 `riscv32im-unknown-none-elf` | * |  | Bare RISC-V (RV32IM ISA)

src/doc/rustc/src/platform-support/aix.md

@@ -0,0 +1,26 @@
+# `powerpc64-ibm-aix`
+
+**Tier: 3**
+
+Rust for AIX operating system, currently only 64-bit PowerPC is supported.
+
+## Target maintainers
+
+- QIU Chaofan `[email protected]`, https://github.com/ecnelises
+- Kai LUO, `[email protected]`, https://github.com/bzEq
+
+## Requirements
+
+This target supports host tools, std and alloc. This target cannot be cross-compiled as for now, mainly because of the unavailability of system linker on other platforms.
+
+Binary built for this target is expected to run on Power7 or newer CPU, and AIX 7.2 or newer version.
+
+Binary format of this platform is [XCOFF](https://www.ibm.com/docs/en/aix/7.2?topic=formats-xcoff-object-file-format). Archive file format is ['AIX big format'](https://www.ibm.com/docs/en/aix/7.2?topic=formats-ar-file-format-big).
+
+## Testing
+
+This target supports running test suites natively, but it's not available to cross-compile and execute in emulator.
+
+## Interoperability with C code
+
+This target supports C code. C code compiled by XL, Open XL and Clang are compatible with Rust. Typical triple of AIX on 64-bit PowerPC of these compilers are also `powerpc64-ibm-aix`.