Revert "nixos/lib/test-driver: enable EFI variable reads at runtime"

nixos/lib/test-driver/test_driver/efi.py

@@ -1,31 +0,0 @@
-from enum import IntEnum
-
-class EfiVariableAttributes(IntEnum):
-    NonVolatile = 0x01
-    BootServiceAccess = 0x02
-    RuntimeAccess = 0x04
-    HardwareErrorRecord = 0x08
-    AuthenticatedWriteAccess = 0x10
-    TimeBasedAuthenticatedWriteAccess = 0x20
-    AppendWrite = 0x40
-    EnhancedAuthenticatedAccess = 0x80
-
-class EfiVariable:
-    """
-        An EFI variable represented by its attributes and raw value in bytes.
-        Generally, the value is not encoded in UTF-8, but UCS-2 or UTF-16-LE.
-    """
-    attributes: EfiVariableAttributes
-    value: bytes
-
-    def __init__(self, value: bytes, attributes: bytes):
-        self.value = value
-        self.attributes = EfiVariableAttributes(attributes)
-
-    def value_as_null_terminated_string(self, encoding: str = 'utf-16-le'):
-        """
-            Most often, variables are encoded with a null-terminated \x00.
-            This function gives you the string in a default encoding of UTF-16-LE
-            stripped of the null terminator.
-        """
-        return self.value.decode(encoding).rstrip('\x00')

nixos/lib/test-driver/test_driver/machine.py

@@ -17,7 +17,6 @@ import tempfile
 import threading
 import time
 
-from test_driver.efi import EfiVariable
 from test_driver.logger import rootlog
 
 CHAR_TO_KEY = {
@@ -1035,33 +1034,6 @@ class Machine:
         """
         self.send_monitor_command(f"hostfwd_add tcp::{host_port}-:{guest_port}")
 
-    def running_under_uefi(self) -> bool:
-        """
-        Returns True if the current environment is running under UEFI, False otherwise.
-        This is achieved by inspecting by the existence of /sys/firmware/efi.
-        """
-        rc, _ = self.execute("test -d /sys/firmware/efi")
-        return (rc == 0)
-
-
-    def read_efi_variable_from_sysfs(self, guid: str, variable_name: str) -> EfiVariable | None:
-        """
-        Read an EFI variable located in efivars sysfs if available.
-        Returns None if the EFI variable does not exist.
-        Raises an assertion error if we are not running under an UEFI environment.
-        """
-        assert self.running_under_uefi(), "This machine is not detected under an UEFI environment"
-        rc, raw_attributes_and_value = self.execute(f"base64 /sys/firmware/efi/efivars/{variable_name}-{guid}")
-        if rc != 0: return None
-        # The return value is a string which is in reality a disguised bytes, we re-encode it properly
-        # using raw_unicode_escape keeping all the escapes properly.
-        # This is not guaranteed to work for all the cases but is good enough for UTF-8/UTF-16 usecases.
-        attributes_and_value = base64.b64decode(raw_attributes_and_value)
-        # First 4 bytes are attributes: https://www.kernel.org/doc/html/latest/filesystems/efivarfs.html
-        attributes = attributes_and_value[:4]
-        value = attributes_and_value[4:]
-        return EfiVariable(value=value, attributes=attributes)
-
     def block(self) -> None:
         """Make the machine unreachable by shutting down eth1 (the multicast
         interface used to talk to the other VMs).  We keep eth0 up so that