A fluid supply system, comprising: a variable displacement piston pump including an adjustable hanger that is movable to a plurality of control positions, the variable displacement piston pump configured to receive a drive torque and, upon receipt of the drive torque, to supply fluid at a pump discharge pressure and flow rate dependent on the control position of the adjustable hanger; a hanger actuator including a pump control pressure inlet port coupled to receive pump control fluid at a fluid pressure, the hanger actuator responsive to the fluid pressure of the pump control fluid to move the adjustable hanger to a control position; and a pump compensator including a mode control pressure port and a pump control pressure outlet port, the pump compensator pump control pressure outlet port in fluid communication with the hanger actuator pump control pressure inlet port, the pump compensator responsive to fluid pressure at the mode control pressure port to operate in either (i) a normal mode, in which the pump compensator controls the fluid pressure of the pump control fluid such that the variable displacement piston pump is controlled in accordance with a variable flow/variable discharge pressure scheme, or (ii) a shutdown mode, in which the pump compensator controls the fluid pressure of the pump control fluid such that the variable displacement piston pump is controlled in accordance with a variable flow/constant discharge pressure scheme, characterized in that: the pump compensator further includes a reference pressure port, a first control pressure port, and a second control pressure port; the pump compensator, in the normal mode, is further responsive to fluid pressure at the first control pressure port and the second control pressure port to control the fluid pressure of the pump control fluid such that a pressure differential between the first control pressure port and the second control pressure port is maintained constant; and the pump compensator, in the shutdown mode, is further responsive to fluid pressure at the first control pressure port and the reference pressure port to control the fluid pressure of the pump control fluid such that a pressure differential between the first control pressure port and the reference control pressure port is maintained constant. a variable displacement piston pump including an adjustable hanger that is movable to a plurality of control positions, the variable displacement piston pump configured to receive a drive torque and, upon receipt of the drive torque, to supply fluid at a pump discharge pressure and flow rate dependent on the control position of the adjustable hanger; a hanger actuator including a pump control pressure inlet port coupled to receive pump control fluid at a fluid pressure, the hanger actuator responsive to the fluid pressure of the pump control fluid to move the adjustable hanger to a control position; and a pump compensator including a mode control pressure port and a pump control pressure outlet port, the pump compensator pump control pressure outlet port in fluid communication with the hanger actuator pump control pressure inlet port, the pump compensator responsive to fluid pressure at the mode control pressure port to operate in either (i) a normal mode, in which the pump compensator controls the fluid pressure of the pump control fluid such that the variable displacement piston pump is controlled in accordance with a variable flow/variable discharge pressure scheme, or (ii) a shutdown mode, in which the pump compensator controls the fluid pressure of the pump control fluid such that the variable displacement piston pump is controlled in accordance with a variable flow/constant discharge pressure scheme, characterized in that: the pump compensator further includes a reference pressure port, a first control pressure port, and a second control pressure port; the pump compensator, in the normal mode, is further responsive to fluid pressure at the first control pressure port and the second control pressure port to control the fluid pressure of the pump control fluid such that a pressure differential between the first control pressure port and the second control pressure port is maintained constant; and the pump compensator, in the shutdown mode, is further responsive to fluid pressure at the first control pressure port and the reference pressure port to control the fluid pressure of the pump control fluid such that a pressure differential between the first control pressure port and the reference control pressure port is maintained constant. the pump compensator further includes a reference pressure port, a first control pressure port, and a second control pressure port; the pump compensator, in the normal mode, is further responsive to fluid pressure at the first control pressure port and the second control pressure port to control the fluid pressure of the pump control fluid such that a pressure differential between the first control pressure port and the second control pressure port is maintained constant; and the pump compensator, in the shutdown mode, is further responsive to fluid pressure at the first control pressure port and the reference pressure port to control the fluid pressure of the pump control fluid such that a pressure differential between the first control pressure port and the reference control pressure port is maintained constant.