Skip to content

Rework fw_cfg and add bootorder entry #170

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Draft
scholzp wants to merge 9 commits into
base: gardenlinux
Choose a base branch
from
Draft

Rework fw_cfg and add bootorder entry #170

Show file tree
Hide file tree
Changes from 3 commits
Commits
Show all changes
9 commits
Select commit Hold shift + click to select a range
fa3cd55
devices: Introduce `u16` and `u64` payloads to `fw_cfg`
scholzp Jun 1, 2026
8e253d9
devices: Add defined defaults to fw_cfg legacy items
scholzp Jun 1, 2026
f7ba097
vmm: Add bootindex to `DiskConfig`
scholzp Jun 5, 2026
03ab3c1
vmm: Allow generating open firmware device paths for virtio devices
scholzp Jun 5, 2026
7a2a2c1
vmm: Expose boot order items
scholzp Jun 5, 2026
ed98bd1
vmm: Populate `bootorder` times of `fw_cfg`
scholzp Jun 5, 2026
9ac85eb
vmm: Make default fw_cfg device not contain binary blobs
scholzp Jun 4, 2026
6c823a4
vmm: Implicitly add `FwCfgConfig` if none is present but required
scholzp Jun 3, 2026
c4ba2b5
X: Enable fw_cfg device for development
scholzp Jun 1, 2026
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
63 changes: 61 additions & 2 deletions devices/src/legacy/fw_cfg.rs
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -79,12 +79,27 @@ pub const PORT_FW_CFG_WIDTH: u64 = 0x10;

const FW_CFG_SIGNATURE: u16 = 0x00;
const FW_CFG_ID: u16 = 0x01;
const FW_CFG_UUID: u16 = 0x02;
const FW_CFG_RAM_SIZE: u16 = 0x03;
const FW_CFG_NOGRAPHIC: u16 = 0x04;
const FW_CFG_NB_CPUS: u16 = 0x05;
const FW_CFG_MACHINE_ID: u16 = 0x06;
const FW_CFG_KERNEL_ADDR: u16 = 0x07;
const FW_CFG_KERNEL_SIZE: u16 = 0x08;
const FW_CFG_KERNEL_CMDLINE: u16 = 0x09;
const FW_CFG_INITRD_ADDR: u16 = 0x0a;
const FW_CFG_INITRD_SIZE: u16 = 0x0b;
const FW_CFG_BOOT_DEVICE: u16 = 0x0c;
const FW_CFG_NUMA: u16 = 0x0d;
const FW_CFG_BOOT_MENU: u16 = 0x0e;
const FW_CFG_MAX_CPUS: u16 = 0x0f;
const FW_CFG_KERNEL_ENTRY: u16 = 0x10;
const FW_CFG_KERNEL_DATA: u16 = 0x11;
const FW_CFG_INITRD_DATA: u16 = 0x12;
const FW_CFG_CMDLINE_ADDR: u16 = 0x13;
const FW_CFG_CMDLINE_SIZE: u16 = 0x14;
const FW_CFG_CMDLINE_DATA: u16 = 0x15;
const FW_CFG_SETUP_ADDR: u16 = 0x16;
const FW_CFG_SETUP_SIZE: u16 = 0x17;
const FW_CFG_SETUP_DATA: u16 = 0x18;
const FW_CFG_FILE_DIR: u16 = 0x19;
Expand Down Expand Up @@ -116,7 +131,9 @@ pub enum FwCfgContent {
Bytes(Vec<u8>),
Slice(&'static [u8]),
File(u64, File),
U64(u64),
U32(u32),
U16(u16),
}

struct FwCfgContentAccess<'a> {
Expand All @@ -139,10 +156,18 @@ impl Read for FwCfgContentAccess<'_> {
Some(mut s) => s.read(buf),
None => Err(ErrorKind::UnexpectedEof)?,
},
FwCfgContent::U64(n) => match n.to_le_bytes().get(self.offset as usize..) {
Some(mut s) => s.read(buf),
None => Err(ErrorKind::UnexpectedEof)?,
},
FwCfgContent::U32(n) => match n.to_le_bytes().get(self.offset as usize..) {
Some(mut s) => s.read(buf),
None => Err(ErrorKind::UnexpectedEof)?,
},
FwCfgContent::U16(n) => match n.to_le_bytes().get(self.offset as usize..) {
Some(mut s) => s.read(buf),
None => Err(ErrorKind::UnexpectedEof)?,
},
}
}
}
Expand All @@ -159,7 +184,9 @@ impl FwCfgContent {
FwCfgContent::Bytes(v) => v.len(),
FwCfgContent::File(offset, f) => (f.metadata()?.len() - offset) as usize,
FwCfgContent::Slice(s) => s.len(),
FwCfgContent::U64(n) => size_of_val(n),
FwCfgContent::U32(n) => size_of_val(n),
FwCfgContent::U16(n) => size_of_val(n),
};
u32::try_from(ret).map_err(|_| std::io::ErrorKind::InvalidInput.into())
}
Expand Down Expand Up @@ -419,10 +446,34 @@ impl FwCfg {
pub fn new(memory: GuestMemoryAtomic<GuestMemoryMmap<AtomicBitmap>>) -> FwCfg {
const DEFAULT_ITEM: FwCfgContent = FwCfgContent::Slice(&[]);
let mut known_items = [DEFAULT_ITEM; FW_CFG_KNOWN_ITEMS];
let file_buf = Vec::from(FwCfgFilesHeader { count_be: 0 }.as_mut_bytes());

known_items[FW_CFG_SIGNATURE as usize] = FwCfgContent::Slice(&FW_CFG_DMA_SIGNATURE);
known_items[FW_CFG_ID as usize] = FwCfgContent::Slice(&FW_CFG_FEATURE);
let file_buf = Vec::from(FwCfgFilesHeader { count_be: 0 }.as_mut_bytes());
known_items[FW_CFG_FILE_DIR as usize] = FwCfgContent::Bytes(file_buf);
known_items[FW_CFG_UUID as usize] = FwCfgContent::Bytes(Default::default()); /* TODO? */

@Coffeeri Coffeeri Jun 12, 2026

Copy link
Copy Markdown

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

What are all these TODO's? Do we need those?

known_items[FW_CFG_RAM_SIZE as usize] = FwCfgContent::U64(0); /* TODO? */
known_items[FW_CFG_NOGRAPHIC as usize] = FwCfgContent::U16(0); /* TODO? */
known_items[FW_CFG_NB_CPUS as usize] = FwCfgContent::U16(0); /* TODO? */
known_items[FW_CFG_MACHINE_ID as usize] = FwCfgContent::U16(0); /* TODO? */
known_items[FW_CFG_KERNEL_ADDR as usize] = FwCfgContent::U32(0); /* TODO? */
known_items[FW_CFG_KERNEL_SIZE as usize] = FwCfgContent::U32(0); /* TODO? */
known_items[FW_CFG_KERNEL_CMDLINE as usize] = FwCfgContent::U32(0); /* TODO? */
known_items[FW_CFG_INITRD_ADDR as usize] = FwCfgContent::U32(0); /* TODO? */
known_items[FW_CFG_INITRD_SIZE as usize] = FwCfgContent::U32(0); /* TODO? */
known_items[FW_CFG_BOOT_DEVICE as usize] = FwCfgContent::U16(0); /* TODO? */
known_items[FW_CFG_NUMA as usize] = FwCfgContent::Bytes(Default::default()); /* TODO? */
known_items[FW_CFG_BOOT_MENU as usize] = FwCfgContent::U16(0); /* TODO? */
known_items[FW_CFG_MAX_CPUS as usize] = FwCfgContent::U16(255); /* TODO? */
known_items[FW_CFG_KERNEL_ENTRY as usize] = FwCfgContent::U32(0); /* TODO? */
known_items[FW_CFG_KERNEL_DATA as usize] = FwCfgContent::Bytes(Default::default()); /* TODO? */
known_items[FW_CFG_INITRD_DATA as usize] = FwCfgContent::Bytes(Default::default()); /* TODO? */
known_items[FW_CFG_CMDLINE_ADDR as usize] = FwCfgContent::U32(0); /* TODO? */
known_items[FW_CFG_CMDLINE_SIZE as usize] = FwCfgContent::U32(0); /* TODO? */
known_items[FW_CFG_CMDLINE_DATA as usize] = FwCfgContent::Bytes(Default::default()); /* TODO? */
known_items[FW_CFG_SETUP_ADDR as usize] = FwCfgContent::U32(0); /* TODO? */
known_items[FW_CFG_SETUP_SIZE as usize] = FwCfgContent::U32(0); /* TODO? */
known_items[FW_CFG_SETUP_DATA as usize] = FwCfgContent::Bytes(Default::default()); /* TODO? */
known_items[FW_CFG_FILE_DIR as usize] = FwCfgContent::Bytes(file_buf); /* TODO? */

FwCfg {
selector: 0,
Expand Down Expand Up @@ -737,10 +788,18 @@ impl FwCfg {
FwCfgContent::File(o, f) => {
f.read_exact_at(data, o + offset as u64).ok()?;
}
FwCfgContent::U64(n) => {
let bytes = n.to_le_bytes();
data.copy_from_slice(&bytes[start..end]);
}
FwCfgContent::U32(n) => {
let bytes = n.to_le_bytes();
data.copy_from_slice(&bytes[start..end]);
}
FwCfgContent::U16(n) => {
let bytes = n.to_le_bytes();
data.copy_from_slice(&bytes[start..end]);
}
}
Some(size as u8)
}
Expand Down
27 changes: 27 additions & 0 deletions vmm/src/config.rs
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -1370,6 +1370,7 @@ impl PciDeviceCommonConfig {
}

impl DiskConfig {
#[cfg(not(feature = "fw_cfg"))]
pub const SYNTAX: &'static str = "Disk parameters \
\"path=<disk_image_path>,readonly=on|off,direct=on|off,iommu=on|off,\
num_queues=<number_of_queues>,queue_size=<size_of_each_queue>,\
Expand All @@ -1382,6 +1383,20 @@ impl DiskConfig {
serial=<serial_number>,backing_files=on|off,sparse=on|off,\
image_type=<raw,qcow2,vhd,vhdx>,lock_granularity=byte-range|full";

#[cfg(feature = "fw_cfg")]
pub const SYNTAX: &'static str = "Disk parameters \

@Coffeeri Coffeeri Jun 12, 2026

Copy link
Copy Markdown

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

I would prefer a concatenation to the existing DiskConfig::SYNTAX, instead of duplicating and having to maintain both.

@scholzp scholzp Jun 30, 2026

Copy link
Copy Markdown
Author

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Sadly, we depend on the pub const. Being a pub const, we do not have a nice way to modify it on runtime without at least implementing some adapter that makes code that consumes the SYNTAX string work.

As this is only a workaround until we make fw_cfg default functionality, I would leave it as is.

\"path=<disk_image_path>,readonly=on|off,direct=on|off,iommu=on|off,\
num_queues=<number_of_queues>,queue_size=<size_of_each_queue>,\
vhost_user=on|off,socket=<vhost_user_socket_path>,\
bw_size=<bytes>,bw_one_time_burst=<bytes>,bw_refill_time=<ms>,\
ops_size=<io_ops>,ops_one_time_burst=<io_ops>,ops_refill_time=<ms>,\
id=<device_id>,pci_segment=<segment_id>,pci_device_id=<pci_slot>,\
rate_limit_group=<group_id>,\
queue_affinity=<list_of_queue_indices_with_their_associated_cpuset>,\
serial=<serial_number>,backing_files=on|off,sparse=on|off,\
image_type=<raw,qcow2,vhd,vhdx>,lock_granularity=byte-range|full,\
bootindex=<index>";

pub fn parse(disk: &str) -> Result<Self> {
let mut parser = OptionParser::new();
parser
Expand Down Expand Up @@ -1409,6 +1424,9 @@ impl DiskConfig {
.add("lock_granularity")
.add_all(PciDeviceCommonConfig::OPTIONS_IOMMU);

#[cfg(feature = "fw_cfg")]
parser.add("bootindex");

parser.parse(disk).map_err(Error::ParseDisk)?;

let path = parser.get("path").map(PathBuf::from);
Expand Down Expand Up @@ -1538,6 +1556,11 @@ impl DiskConfig {

let pci_common = PciDeviceCommonConfig::parse(disk)?;

#[cfg(feature = "fw_cfg")]
let bootindex = parser
.convert::<u16>("bootindex")
.map_err(Error::ParseDisk)?;

Ok(DiskConfig {
pci_common,
path,
Expand All @@ -1557,6 +1580,8 @@ impl DiskConfig {
sparse,
image_type,
lock_granularity,
#[cfg(feature = "fw_cfg")]
bootindex,
})
}

Expand Down Expand Up @@ -4125,6 +4150,8 @@ mod unit_tests {
sparse: true,
image_type: ImageType::Unknown,
lock_granularity: LockGranularityChoice::default(),
#[cfg(feature = "fw_cfg")]
bootindex: Default::default(),
}
}

Expand Down
3 changes: 3 additions & 0 deletions vmm/src/vm_config.rs
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -383,6 +383,9 @@ pub struct DiskConfig {
pub image_type: ImageType,
#[serde(default)]
pub lock_granularity: LockGranularityChoice,
#[cfg(feature = "fw_cfg")]
#[serde(default)]
pub bootindex: Option<u16>,
}

impl ApplyLandlock for DiskConfig {
Expand Down