Invalidate CMOS checksum after flashing

src/app/bios.rs

@@ -15,8 +15,8 @@
 use std::vars::{get_boot_item, get_boot_order, set_boot_item, set_boot_order};
 
 use super::{
-    pci_mcfg, shell, Component, UefiMapper, FIRMWARECAP, FIRMWAREDIR, FIRMWARENSH, FIRMWAREROM,
-    H2OFFT, IFLASHV, UEFIFLASH,
+    cmos, pci_mcfg, shell, Component, UefiMapper, FIRMWARECAP, FIRMWAREDIR, FIRMWARENSH,
+    FIRMWAREROM, H2OFFT, IFLASHV, UEFIFLASH,
 };
 
 fn copy_region(
@@ -37,7 +37,7 @@
             if base < limit && limit < old_data.len() {
                 &old_data[base..limit + 1]
             } else {
                 return Err(format!("old region {:#X}:{:#X} is invalid", base, limit));
             }
         }
         None => return Err("missing old region".to_string()),
@@ -48,7 +48,7 @@
             if base < limit && limit < new_data.len() {
                 &mut new_data[base..limit + 1]
             } else {
                 return Err(format!("new region {:#X}:{:#X} is invalid", base, limit));
             }
         }
         None => return Err("missing new region".to_string()),
@@ -512,6 +512,13 @@
                 }
                 println!();
             }
+
+            // Invalidate the 2-byte CMOS checksum to force writing the option defaults.
+            let mut cmos = cmos::Cmos::default();
+            let old_hi = cmos.read(123);
+            let old_lo = cmos.read(124);
+            cmos.write(123, !old_hi);
+            cmos.write(124, !old_lo);
         } else {
             find(FIRMWARENSH)?;
 
@@ -531,7 +538,7 @@
                 println!("Failed to preserve boot order");
             }
 
             let cmd = format!("{} {} bios flash", FIRMWARENSH, FIRMWAREDIR);
             let status = shell(&cmd)?;
 
             #[allow(clippy::single_match)]

src/app/cmos.rs

@@ -0,0 +1,33 @@
+// SPDX-License-Identifier: GPL-3.0-only
+
+use hwio::{Io, Pio};
+
+pub struct Cmos {
+    port: Pio<u8>,
+    data: Pio<u8>,
+}
+
+impl Cmos {
+    pub fn new(port: u16) -> Self {
+        Self {
+            port: Pio::<u8>::new(port),
+            data: Pio::<u8>::new(port + 1),
+        }
+    }
+
+    pub fn read(&mut self, addr: u8) -> u8 {
+        self.port.write(addr);
+        self.data.read()
+    }
+
+    pub fn write(&mut self, addr: u8, data: u8) {
+        self.port.write(addr);
+        self.data.write(data);
+    }
+}
+
+impl Default for Cmos {
+    fn default() -> Self {
+        Self::new(0x70)
+    }
+}

src/app/mod.rs

@@ -28,6 +28,7 @@ pub use self::mapper::UefiMapper;
 pub use self::pci::{pci_mcfg, pci_read};
 
 mod bios;
+mod cmos;
 mod component;
 mod ec;
 mod mapper;