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Merged
Lencerf merged 1 commit into from
Mar 8, 2026
Merged

feat(fw_cfg): add CPU count and memory size #423

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2 changes: 2 additions & 0 deletions alioth/src/board/board_x86_64/board_x86_64.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -454,6 +454,8 @@ where
dev.add_acpi(acpi_table).context(error::FwCfg)?;
let mem_regions = memory.mem_region_entries();
dev.add_e820(&mem_regions).context(error::FwCfg)?;
dev.add_ram_size(self.config.mem.size);
dev.add_cpu_count(self.config.cpu.count);
}
Ok(())
}
Expand Down
24 changes: 23 additions & 1 deletion alioth/src/device/fw_cfg/fw_cfg.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -51,7 +51,7 @@ use crate::mem::emulated::{Action, Mmio};
use crate::mem::mapped::RamBus;
#[cfg(target_arch = "x86_64")]
use crate::mem::{MemRegionEntry, MemRegionType};
use crate::utils::endian::{Bu16, Bu32, Bu64, Lu32};
use crate::utils::endian::{Bu16, Bu32, Bu64, Lu16, Lu32, Lu64};

#[cfg(target_arch = "x86_64")]
use self::acpi::create_acpi_loader;
Expand Down Expand Up @@ -104,7 +104,9 @@ pub enum FwCfgContent {
Bytes(Vec<u8>),
Slice(&'static [u8]),
File(u64, File),
Lu16(Lu16),
Lu32(Lu32),
Lu64(Lu64),
}

struct FwCfgContentAccess<'a> {
Expand All @@ -127,10 +129,18 @@ impl Read for FwCfgContentAccess<'_> {
Some(mut s) => s.read(buf),
None => Err(ErrorKind::UnexpectedEof)?,
},
FwCfgContent::Lu16(n) => match n.as_bytes().get(self.offset as usize..) {
Some(mut s) => s.read(buf),
None => Err(ErrorKind::UnexpectedEof)?,
},
FwCfgContent::Lu32(n) => match n.as_bytes().get(self.offset as usize..) {
Some(mut s) => s.read(buf),
None => Err(ErrorKind::UnexpectedEof)?,
},
FwCfgContent::Lu64(n) => match n.as_bytes().get(self.offset as usize..) {
Some(mut s) => s.read(buf),
None => Err(ErrorKind::UnexpectedEof)?,
},
}
}
}
Expand All @@ -147,7 +157,9 @@ impl FwCfgContent {
FwCfgContent::Bytes(v) => v.len(),
FwCfgContent::File(offset, f) => (f.metadata()?.len() - offset) as usize,
FwCfgContent::Slice(s) => s.len(),
FwCfgContent::Lu16(n) => size_of_val(n),
FwCfgContent::Lu32(n) => size_of_val(n),
FwCfgContent::Lu64(n) => size_of_val(n),
};
u32::try_from(ret).map_err(|_| std::io::ErrorKind::InvalidInput.into())
}
Expand All @@ -173,7 +185,9 @@ impl FwCfgContent {
}
}
}
FwCfgContent::Lu16(n) => n.as_bytes().get(offset as usize).copied(),
FwCfgContent::Lu32(n) => n.as_bytes().get(offset as usize).copied(),
FwCfgContent::Lu64(n) => n.as_bytes().get(offset as usize).copied(),
}
}
}
Expand Down Expand Up @@ -266,6 +280,14 @@ impl FwCfg {
self.get_file_dir_mut()[0..4].copy_from_slice(header.as_bytes());
}

pub fn add_ram_size(&mut self, size: u64) {
self.known_items[FW_CFG_RAM_SIZE as usize] = FwCfgContent::Lu64(size.into());
}

pub fn add_cpu_count(&mut self, count: u16) {
self.known_items[FW_CFG_NB_CPUS as usize] = FwCfgContent::Lu16(count.into());
}

#[cfg(target_arch = "x86_64")]
pub(crate) fn add_e820(&mut self, mem_regions: &[(u64, MemRegionEntry)]) -> Result<()> {
let mut bytes = vec![];
Expand Down
14 changes: 11 additions & 3 deletions alioth/src/device/fw_cfg/fw_cfg_test.rs
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Expand Up @@ -34,7 +34,9 @@ fn create_file_with_content(content: &str) -> io::Result<File> {
#[case(FwCfgContent::Bytes(vec![0x01, 0x02, 0x03]), 3)]
#[case(FwCfgContent::default(), 0)]
#[case(FwCfgContent::Slice(b"abcd"), 4)]
#[case(FwCfgContent::Lu16(1234.into()), 2)]
#[case(FwCfgContent::Lu32(1234.into()), 4)]
#[case(FwCfgContent::Lu64(1234.into()), 8)]
fn test_fw_cfg_content_size(#[case] content: FwCfgContent, #[case] size: u32) {
assert_matches!(content.size(), Ok(v) if v == size);
}
Expand All @@ -51,7 +53,9 @@ fn test_fw_cfg_content_file_size() {
#[case(FwCfgContent::Bytes(vec![0x01, 0x02, 0x03]), 2, Some(0x03))]
#[case(FwCfgContent::default(), 1, None)]
#[case(FwCfgContent::Slice(b"abcd"), 0, Some(b'a'))]
#[case(FwCfgContent::Lu32(0xab_cd_u32.into()), 0, Some(0xcd))]
#[case(FwCfgContent::Lu16(0x12_u16.into()), 0, Some(0x12))]
#[case(FwCfgContent::Lu32(0xabcd_u32.into()), 1, Some(0xab))]
#[case(FwCfgContent::Lu64(0xef_abcd_u64.into()), 2, Some(0xef))]
fn test_fw_cfg_content_read(
#[case] content: FwCfgContent,
#[case] offset: u32,
Expand All @@ -75,8 +79,12 @@ fn test_fw_cfg_content_file_read() {
#[case(FwCfgContent::Bytes(vec![0x01, 0x02, 0x03]), 4, &[])]
#[case(FwCfgContent::default(), 1, &[])]
#[case(FwCfgContent::Slice(b"abcd"), 0, &[b'a', b'b', b'c', b'd'])]
#[case(FwCfgContent::Lu32(0xab_cd_u32.into()), 0, &[0xcd, 0xab, 0x00, 0x00])]
#[case(FwCfgContent::Lu32(0xab_cd_u32.into()), 5, &[])]
#[case(FwCfgContent::Lu16(0xabcd_u16.into()), 0, &[0xcd, 0xab])]
#[case(FwCfgContent::Lu16(0xabcd_u16.into()), 2, &[])]
#[case(FwCfgContent::Lu32(0x1234_abcd_u32.into()), 0, &[0xcd, 0xab, 0x34, 0x12])]
#[case(FwCfgContent::Lu32(0x1234_abcd_u32.into()), 5, &[])]
#[case(FwCfgContent::Lu64(0xfcfe_1234_abcd_u64.into()), 0, &[0xcd, 0xab, 0x34, 0x12, 0xfe, 0xfc])]
#[case(FwCfgContent::Lu64(0xfcfe_1234_abcd_u64.into()), 8, &[])]
fn test_fw_cfg_content_access(
#[case] content: FwCfgContent,
#[case] offset: u32,
Expand Down