change riscv64a23 target reqirements comments: linux kernel 6.8.0, glibc 2.39

Author: ZhongyaoChen

compiler/rustc_target/src/spec/targets/riscv64a23_unknown_linux_gnu.rs

@@ -6,7 +6,7 @@ pub(crate) fn target() -> Target {
     Target {
         llvm_target: "riscv64-unknown-linux-gnu".into(),
         metadata: TargetMetadata {
-            description: Some("RISC-V Linux (kernel 4.20, glibc 2.29)".into()),
+            description: Some("RISC-V Linux (kernel 6.8.0, glibc 2.39)".into()),
             tier: Some(3),
             host_tools: Some(true),
             std: Some(true),

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

@@ -389,7 +389,7 @@ target | std | host | notes
 [`riscv64gc-unknown-nuttx-elf`](platform-support/nuttx.md) | ✓ |  | RISC-V 64bit with NuttX
 [`riscv64gc-unknown-openbsd`](platform-support/openbsd.md) | ✓ | ✓ | OpenBSD/riscv64
 [`riscv64imac-unknown-nuttx-elf`](platform-support/nuttx.md) | ✓ |  | RISC-V 64bit with NuttX
-[`riscv64a23-unknown-linux-gnu`](platform-support/riscv64a23-unknown-linux-gnu.md) | ✓ | ✓ | RISC-V Linux (kernel 4.20+, glibc 2.29)
+[`riscv64a23-unknown-linux-gnu`](platform-support/riscv64a23-unknown-linux-gnu.md) | ✓ | ✓ | RISC-V Linux (kernel 6.8.0+, glibc 2.39)
 [`s390x-unknown-linux-musl`](platform-support/s390x-unknown-linux-musl.md) | ✓ |  | S390x Linux (kernel 3.2, musl 1.2.3)
 `sparc-unknown-linux-gnu` | ✓ |  | 32-bit SPARC Linux
 [`sparc-unknown-none-elf`](./platform-support/sparc-unknown-none-elf.md) | * |  | Bare 32-bit SPARC V7+

src/doc/rustc/src/platform-support/riscv64a23-unknown-linux-gnu.md

@@ -12,10 +12,9 @@ This target will enable all mandary features of rva23u64 and rva23s64 by default
 
 ## Requirements
 
-This target requires:
+This target can be sucessfully build on the following platform: ubuntu 24.04 (Linux Kernel version 6.8.0, glibc 2.39).
 
-* Linux Kernel version 4.20 or later
-* glibc 2.17 or later
+Other platforms may work, but are not tested. Please contanct if you encounter any issues.
 
 ## Building the target