fix(boot): read the ACPI RSDP before taking the memory-map key

ExitBootServices failed with EFI_INVALID_PARAMETER because Print ran
after GetMemoryMap, so the console output could change the memory map
and invalidate MapKey. Locate the RSDP and print it before GetMemoryMap.

boot/boot.c

@@ -500,6 +500,11 @@ EFI_STATUS ExitBootServicesAndJumpToKernel(
     // ==========================
     Print(L"Exiting Boot Services...\r\n");
 
+    // Capture the RSDP before GetMemoryMap: any boot-service call that
+    // allocates after the map key is taken invalidates ExitBootServices.
+    UINT64 AcpiRsdp = FindAcpiRsdp(SystemTable);
+    Print(L"ACPI RSDP: 0x%lx\r\n", AcpiRsdp);
+
     UINTN MemoryMapSize = 0;
     UINTN MapKey;
     UINTN DescriptorSize;
@@ -546,8 +551,7 @@ EFI_STATUS ExitBootServicesAndJumpToKernel(
     BootInfo.framebuffer_pitch = framebuffer_pitch;
     BootInfo.framebuffer_format = framebuffer_format;
     BootInfo.system_table = 0;
-    BootInfo.acpi_rsdp = FindAcpiRsdp(SystemTable);
-    Print(L"ACPI RSDP: 0x%lx\r\n", BootInfo.acpi_rsdp);
+    BootInfo.acpi_rsdp = AcpiRsdp;
 
     static boot_info_t static_boot_info;
     static_boot_info = BootInfo;