diff --git a/alioth/src/board/board_x86_64/board_x86_64.rs b/alioth/src/board/board_x86_64/board_x86_64.rs
index 3c9b863a..00f7463f 100644
--- a/alioth/src/board/board_x86_64/board_x86_64.rs
+++ b/alioth/src/board/board_x86_64/board_x86_64.rs
@@ -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(())
     }
diff --git a/alioth/src/device/fw_cfg/fw_cfg.rs b/alioth/src/device/fw_cfg/fw_cfg.rs
index 46cafb90..14ab4543 100644
--- a/alioth/src/device/fw_cfg/fw_cfg.rs
+++ b/alioth/src/device/fw_cfg/fw_cfg.rs
@@ -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;
@@ -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> {
@@ -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)?,
+            },
         }
     }
 }
@@ -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())
     }
@@ -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(),
         }
     }
 }
@@ -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![];
diff --git a/alioth/src/device/fw_cfg/fw_cfg_test.rs b/alioth/src/device/fw_cfg/fw_cfg_test.rs
index 576b385c..abe3858c 100644
--- a/alioth/src/device/fw_cfg/fw_cfg_test.rs
+++ b/alioth/src/device/fw_cfg/fw_cfg_test.rs
@@ -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);
 }
@@ -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,
@@ -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,