tc_build: kernel: Build ppc64_guest_defconfig with LLVM=1

Now that commit 9d90161ca5c7 ("powerpc/64: Force ELFv2 when building
with LLVM linker") is in mainline, we can ditch ld.bfd for powerpc64 big
endian. Additionally, the integrated assembler has worked since LLVM
14.0.2 just like for powerpc64le, so hoist those decisions into
PowerPC64KernelBuilder and make PowerPC64LEKernelBuilder a subclass of
it, so that both builds can use LLVM=1 for all LLVM versions that the
kernel currently supports.

Signed-off-by: Nathan Chancellor <[email protected]>

tc_build/kernel.py

@@ -16,7 +16,7 @@ class KernelBuilder(Builder):
     # If the user supplies their own kernel source, it must be at least this
     # version to ensure that all the build commands work, as the build commands
     # were written to target at least this version.
-    MINIMUM_SUPPORTED_VERSION = (6, 1, 7)
+    MINIMUM_SUPPORTED_VERSION = (6, 5, 0)
 
     def __init__(self, arch):
         super().__init__()
@@ -196,11 +196,16 @@ def __init__(self):
         self.config_targets = ['ppc64_guest_defconfig', 'disable-werror.config']
         self.cross_compile = 'powerpc64-linux-gnu-'
 
-        # https://github.com/ClangBuiltLinux/linux/issues/602
-        self.make_variables['LD'] = self.cross_compile + 'ld'
+    # https://github.com/llvm/llvm-project/commit/33504b3bbe10d5d4caae13efcb99bd159c126070
+    def can_use_ias(self):
+        return self.toolchain_version >= (14, 0, 2)
+
+    # https://github.com/ClangBuiltLinux/linux/issues/1601
+    def needs_binutils(self):
+        return True
 
 
-class PowerPC64LEKernelBuilder(PowerPCKernelBuilder):
+class PowerPC64LEKernelBuilder(PowerPC64KernelBuilder):
 
     def __init__(self):
         super().__init__()
@@ -216,14 +221,6 @@ def build(self):
 
         super().build()
 
-    # https://github.com/llvm/llvm-project/commit/33504b3bbe10d5d4caae13efcb99bd159c126070
-    def can_use_ias(self):
-        return self.toolchain_version >= (14, 0, 2)
-
-    # https://github.com/ClangBuiltLinux/linux/issues/1601
-    def needs_binutils(self):
-        return True
-
 
 class RISCVKernelBuilder(KernelBuilder):