diff options
| -rw-r--r-- | devices/src/pci/pci_configuration.rs | 21 |
1 files changed, 20 insertions, 1 deletions
diff --git a/devices/src/pci/pci_configuration.rs b/devices/src/pci/pci_configuration.rs index 5f230af..566d9b8 100644 --- a/devices/src/pci/pci_configuration.rs +++ b/devices/src/pci/pci_configuration.rs @@ -291,7 +291,7 @@ impl PciConfiguration { /// Writes a 32bit register to `reg_idx` in the register map. pub fn write_reg(&mut self, reg_idx: usize, value: u32) { if let Some(r) = self.registers.get_mut(reg_idx) { - *r = value & self.writable_bits[reg_idx]; + *r = (*r & !self.writable_bits[reg_idx]) | (value & self.writable_bits[reg_idx]); } else { warn!("bad PCI register write {}", reg_idx); } @@ -626,4 +626,23 @@ mod tests { assert_eq!(subclass, 0x01); assert_eq!(prog_if, 0x5a); } + + #[test] + fn read_only_bits() { + let mut cfg = PciConfiguration::new( + 0x1234, + 0x5678, + PciClassCode::MultimediaController, + &PciMultimediaSubclass::AudioController, + Some(&TestPI::Test), + PciHeaderType::Device, + 0xABCD, + 0x2468, + ); + + // Attempt to overwrite vendor ID and device ID, which are read-only + cfg.write_reg(0, 0xBAADF00D); + // The original vendor and device ID should remain. + assert_eq!(cfg.read_reg(0), 0x56781234); + } } |