Add x86_64 kernel bring-up with build-selected platform adapters

src/arch/x86_64/arch.x86_64.boot.pas

@@ -0,0 +1,83 @@
+// Copyright 2026 Aaron Hance
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+// http://www.apache.org/licenses/LICENSE-2.0
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+unit arch.x86_64.boot;
+
+interface
+
+procedure kmain(info: pointer; magic: uint32); cdecl;
+
+implementation
+
+uses io.stdio, core.strings, driver.storage.fdtable, arch.x86_64.proc.sched, proc.mgr, arch.x86_64.context, arch.x86_64.irq, memory.heap, debug.early, arch.x86_64.debug, arch.x86_64.isr, boot.multiboot,
+    arch.x86_64.memory.physical, arch.x86_64.memory.virtual;
+
+function long_mode_active: boolean; assembler; nostackframe;
+asm
+    mov ecx, $C0000080
+    rdmsr
+    shr eax, 10
+    and eax, 1
+end;
+
+procedure kmain(info: pointer; magic: uint32); cdecl; [public, alias: 'kmain'];
+var
+    wide: PtrUInt;
+begin
+    arch.x86_64.debug.init;
+    arch.x86_64.isr.init;
+    puts('ASURO x86_64: entered Pascal'#13#10);
+    if (magic <> $2BADB002) or (info = nil) then begin
+        puts('FAIL: Multiboot handoff'#13#10);
+        bootstrap_halt;
+    end;
+    if (sizeof(pointer) <> 8) or (sizeof(PtrUInt) <> 8) or
+       (sizeof(SizeUInt) <> 8) or (sizeof(uint32) <> 4) then begin
+        puts('FAIL: native type widths'#13#10);
+        bootstrap_halt;
+    end;
+    wide := PtrUInt($100000000) + PtrUInt(magic);
+    if (wide shr 32 <> 1) or not long_mode_active then begin
+        puts('FAIL: long mode or 64-bit arithmetic'#13#10);
+        bootstrap_halt;
+    end;
+    puts('PASS: long mode, Multiboot handoff, 64-bit Pascal types'#13#10);
+    arch.x86_64.isr.UnitTest;
+    arch.x86_64.memory.physical.init(Pmultiboot_info_t(info));
+    arch.x86_64.memory.physical.UnitTest;
+    arch.x86_64.memory.virtual.init;
+    arch.x86_64.memory.virtual.UnitTest;
+    memory.heap.init;
+    memory.heap.UnitTest;
+    core.strings.UnitTest;
+    io.stdio.init;
+    arch.x86_64.irq.init;
+    arch.x86_64.irq.UnitTest;
+    arch.x86_64.context.UnitTest;
+    driver.storage.fdtable.UnitTest;
+    proc.mgr.init;
+    arch.x86_64.proc.sched.init;
+    arch.x86_64.proc.sched.UnitTest;
+    {$ifdef ASURO_TEST_UD}
+    arch.x86_64.isr.testFatal(6);
+    {$endif}
+    {$ifdef ASURO_TEST_PF}
+    arch.x86_64.isr.testFatal(14);
+    {$endif}
+    {$ifdef ASURO_TEST_DF}
+    arch.x86_64.isr.testFatal(8);
+    {$endif}
+    puts('ASURO x86_64: bootstrap complete; interrupts disabled'#13#10);
+    bootstrap_halt;
+end;
+
+end.