ch: Fix various misspelled words

Misspellings were identified by https://github.com/marketplace/actions/check-spelling
* Initial corrections suggested by Google Sheets
* Additional corrections by Google Chrome auto-suggest
* Some manual corrections

Signed-off-by: Josh Soref <jsoref@users.noreply.github.com>

CONTRIBUTING.md

@@ -88,5 +88,5 @@ Fixes #88
 Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
 ```
 
-Then, after the correspoding PR is merged, Github will automatically close that issue when parsing the
+Then, after the corresponding PR is merged, Github will automatically close that issue when parsing the
 [commit message](https://help.github.com/articles/closing-issues-via-commit-messages/).

arch/src/aarch64/fdt.rs

@@ -99,7 +99,7 @@ pub fn create_fdt<T: DeviceInfoForFDT + Clone + Debug, S: ::std::hash::BuildHash
     initrd: &Option<InitramfsConfig>,
     pci_space_address: &Option<(u64, u64)>,
 ) -> Result<Vec<u8>> {
-    // Alocate stuff necessary for the holding the blob.
+    // Allocate stuff necessary for the holding the blob.
     let mut fdt = vec![0; FDT_MAX_SIZE];
 
     allocate_fdt(&mut fdt)?;
@@ -402,7 +402,7 @@ fn create_gic_node(fdt: &mut Vec<u8>, gic_device: &dyn GICDevice) -> Result<()>
 
     if gic_device.msi_compatible() {
         append_begin_node(fdt, "msic")?;
-        append_property_string(fdt, "compatible", gic_device.msi_compatiblility())?;
+        append_property_string(fdt, "compatible", gic_device.msi_compatibility())?;
         append_property_null(fdt, "msi-controller")?;
         append_property_u32(fdt, "phandle", MSI_PHANDLE)?;
         let msi_reg_prop = generate_prop64(gic_device.msi_properties());

arch/src/aarch64/gic.rs

@@ -36,7 +36,7 @@ pub trait GICDevice {
     }
 
     /// Returns the MSI compatibility property of the device
-    fn msi_compatiblility(&self) -> &str {
+    fn msi_compatibility(&self) -> &str {
         ""
     }
 

arch/src/aarch64/gicv3_its.rs

@@ -49,7 +49,7 @@ pub mod kvm {
             true
         }
 
-        fn msi_compatiblility(&self) -> &str {
+        fn msi_compatibility(&self) -> &str {
             "arm,gic-v3-its"
         }
 

arch/src/aarch64/layout.rs

@@ -37,7 +37,7 @@
 //           |                                                               |
 // 144 M     +---------------------------------------------------------------|
 //           |                                                               |
-//           |                    Reserverd (now GIC is here)                |
+//           |                    Reserved (now GIC is here)                 |
 //           |                                                               |
 // 0GB       +---------------------------------------------------------------+
 //

arch/src/aarch64/mod.rs

@@ -210,10 +210,10 @@ fn get_fdt_addr(mem: &GuestMemoryMmap) -> u64 {
 pub fn get_host_cpu_phys_bits() -> u8 {
     // The value returned here is used to determine the physical address space size
     // for a VM (IPA size).
-    // In recent kernel versions, the maxium IPA size supported by the host can be
+    // In recent kernel versions, the maximum IPA size supported by the host can be
     // known by querying cap KVM_CAP_ARM_VM_IPA_SIZE. And the IPA size for a
     // guest can be configured smaller.
-    // But in Cloud-Hypervisor we simply use the maxium value for the VM.
+    // But in Cloud-Hypervisor we simply use the maximum value for the VM.
     // Reference https://lwn.net/Articles/766767/.
     //
     // The correct way to query KVM_CAP_ARM_VM_IPA_SIZE is via rust-vmm/kvm-ioctls,

devices/src/legacy/rtc_pl031.rs

@@ -20,7 +20,7 @@ use vm_device::BusDevice;
 // From 0x0 to 0x1C we have following registers:
 const RTCDR: u64 = 0x0; // Data Register.
 const RTCMR: u64 = 0x4; // Match Register.
-const RTCLR: u64 = 0x8; // Load Regiser.
+const RTCLR: u64 = 0x8; // Load Register.
 const RTCCR: u64 = 0xc; // Control Register.
 const RTCIMSC: u64 = 0x10; // Interrupt Mask Set or Clear Register.
 const RTCRIS: u64 = 0x14; // Raw Interrupt Status.

docs/api.md

@@ -12,7 +12,7 @@
         * [Reboot a Virtual Machine](#reboot-a-virtual-machine)
         * [Shut a Virtual Machine Down](#shut-a-virtual-machine-down)
     + [Command Line Interface](#command-line-interface)
-    + [REST API and CLI Architecural Relationship](#rest-api-and-cli-architectural-relationship)
+    + [REST API and CLI Architectural Relationship](#rest-api-and-cli-architectural-relationship)
   * [Internal API](#internal-api)
     + [Goals and Design](#goals-and-design)
   * [End to End Example](#end-to-end-example)

docs/hotplug.md

@@ -63,7 +63,7 @@ As per adding CPUs to the guest, after a reboot the VM will be running with the
 
 ## Memory Hot Plug
 
-Extra memory can be added from a runing Cloud Hypervisor instance. This is controlled by two mechanisms:
+Extra memory can be added from a running Cloud Hypervisor instance. This is controlled by two mechanisms:
 
 1. Allocating some of the guest physical address space for hotplug memory.
 2. Making a HTTP API request to the VMM to ask for a new amount of RAM to be assigned to the VM. In the case of expanding the memory for the VM the new memory will be hotplugged into the running VM, if reducing the size of the memory then change will take effect after the next reboot.

docs/intel_sgx.md

@@ -8,7 +8,7 @@ the host kernel. The required Linux and KVM changes can be found in the
 [KVM SGX Tree](https://github.com/intel/kvm-sgx).
 
 Utilizing SGX in the guest requires a kernel/OS with SGX support, e.g. a kernel
-buit using the [SGX Linux Development Tree](https://github.com/jsakkine-intel/linux-sgx.git)
+built using the [SGX Linux Development Tree](https://github.com/jsakkine-intel/linux-sgx.git)
 or the [KVM SGX Tree](https://github.com/intel/kvm-sgx). Running KVM SGX as the
 guest kernel allows nested virtualization of SGX.
 

docs/networking.md

@@ -1,6 +1,6 @@
 # How to use networking
 
-cloud-hypervisor can emulate one or more virtual network interfaces, represented at the hypervisor host by [tap devices](https://www.kernel.org/doc/Documentation/networking/tuntap.txt). This guide briefly describes, in a manual and distribution neutral way, how to setup and use networking with cloud-hypevisor.
+cloud-hypervisor can emulate one or more virtual network interfaces, represented at the hypervisor host by [tap devices](https://www.kernel.org/doc/Documentation/networking/tuntap.txt). This guide briefly describes, in a manual and distribution neutral way, how to setup and use networking with cloud-hypervisor.
 
 ## Multiple queue support for net devices ##
 
@@ -14,7 +14,7 @@ Note:
 
 - Currently, it does not support to use ethtool to change the combined queue numbers in guest.
 - Multiple queue is enabled for vhost-user-net backend in cloud-hypervisor, however, multiple thread is not added to handle mq, thus, the performance for vhost-user-net backend is not supposed to be improved. The multiple thread will be added for backend later.
-- Performance test for vhost-user-net will be covered once vhost-user-net backend has mulitple thread supported.
+- Performance test for vhost-user-net will be covered once vhost-user-net backend has multiple thread supported.
 - Performance test for virtio-net is done by comparing 2 queue pairs with 1 queue pairs, that to run 2 iperf3 sessions in the same test environments, throughput is improved about 37%.
 
 ## Start cloud-hypervisor with net devices

docs/snapshot_restore.md

@@ -54,7 +54,7 @@ drwxr-xr-x 47 foo bar       4096 Jul 22 11:47 ../
 In this particular example, we can observe that 2 memory region files were
 created. That is explained by the size of the guest RAM, which is 4GiB in this
 case. Because it exceeds 3GiB (which is where we can find a ~1GiB memory hole),
-Cloud-Hypervisor needs 2 distincts memory regions to be created. Each memory
+Cloud-Hypervisor needs 2 distinct memory regions to be created. Each memory
 region's content is stored through a dedicated file, which explains why we end
 up with 2 different files, the first one containing the guest RAM range 0-3GiB
 and the second one containing the guest RAM range 3-4GiB.
@@ -63,7 +63,7 @@ and the second one containing the guest RAM range 3-4GiB.
 and state. The configuration bits are used to create a similar virtual machine
 with the correct amount of CPUs, RAM, and other expected devices. The state
 bits are used to restore each component in the state it was left before the
-snapshot occured.
+snapshot occurred.
 
 ## Restore a Cloud-Hypervisor VM
 

pci/src/configuration.rs

@@ -64,7 +64,7 @@ impl PciClassCode {
     }
 }
 
-/// A PCI sublcass. Each class in `PciClassCode` can specify a unique set of subclasses. This trait
+/// A PCI subclass. Each class in `PciClassCode` can specify a unique set of subclasses. This trait
 /// is implemented by each subclass. It allows use of a trait object to generate configurations.
 pub trait PciSubclass {
     /// Convert this subclass to the value used in the PCI specification.

pci/src/vfio.rs

@@ -785,7 +785,7 @@ impl PciDevice for VfioPciDevice {
                 // We need to allocate a guest MMIO address range for that BAR.
                 // In case the BAR is mappable directly, this means it might be
                 // set as user memory region, which expects to deal with 4K
-                // pages. Therefore, the aligment has to be set accordingly.
+                // pages. Therefore, the alignment has to be set accordingly.
                 let bar_alignment = if (bar_id == VFIO_PCI_ROM_REGION_INDEX)
                     || (self.device.get_region_flags(bar_id) & VFIO_REGION_INFO_FLAG_MMAP != 0)
                 {

qcow/src/qcow.rs

@@ -1056,7 +1056,7 @@ impl QcowFile {
             // Free the previously used cluster if one exists. Modified tables are always
             // witten to new clusters so the L1 table can be committed to disk after they
             // are and L1 never points at an invalid table.
-            // The index must be valid from when it was insterted.
+            // The index must be valid from when it was inserted.
             let addr = self.l1_table[l1_index];
             if addr != 0 {
                 self.unref_clusters.push(addr);
@@ -1354,7 +1354,7 @@ impl QcowFile {
     fn sync_caches(&mut self) -> std::io::Result<()> {
         // Write out all dirty L2 tables.
         for (l1_index, l2_table) in self.l2_cache.iter_mut().filter(|(_k, v)| v.dirty()) {
-            // The index must be valid from when we insterted it.
+            // The index must be valid from when we inserted it.
             let addr = self.l1_table[*l1_index];
             if addr != 0 {
                 self.raw_file.write_pointer_table(

release-notes.md

@@ -318,7 +318,7 @@ Highlights for `cloud-hypervisor` version 0.7.0 include:
 Further to our effort to support modifying a running guest we now support
 hotplug and unplug of the following virtio backed devices: block, network,
 pmem, virtio-fs and vsock. This functionality is available on the (default) PCI
-based tranport and is exposed through the HTTP API. The `ch-remote` utility
+based transport and is exposed through the HTTP API. The `ch-remote` utility
 provides a CLI for adding or removing these device types after the VM has
 booted. User can use the `id` parameter on the devices to choose names for
 devices to ease their removal.
@@ -434,7 +434,7 @@ When choosing to offload the paravirtualized block and networking I/O to an
 external process (through the `vhost-user` protocol), Cloud Hypervisor now
 automatically spawns its default `vhost-user-blk` and `vhost-user-net` backends
 into their own, separate processes.
-This provides a seamless parvirtualized I/O user experience for those who want
+This provides a seamless paravirtualized I/O user experience for those who want
 to run their guest I/O into separate executions contexts.
 
 ### Command Line Interface
@@ -580,7 +580,7 @@ default Cloud Hypervisor I/O architecture.
 
 ### Guest pause and resume
 
-As an initial requiremnt for enabling live migration, we added support for
+As an initial requirement for enabling live migration, we added support for
 pausing and resuming any VMM components. As an intermediate step towards live
 migration, the upcoming guest snapshotting feature will be based on the pause
 and resume capabilities.

scripts/run_integration_tests_aarch64.sh

@@ -173,9 +173,9 @@ if [ $RES -ne 0 ]; then
     exit 1
 fi
 
-# Create tap interface without multipe queues support for vhost_user_net test.
+# Create tap interface without multiple queues support for vhost_user_net test.
 sudo ip tuntap add name vunet-tap0 mode tap
-# Create tap interface with multipe queues support for vhost_user_net test.
+# Create tap interface with multiple queues support for vhost_user_net test.
 sudo ip tuntap add name vunet-tap1 mode tap multi_queue
 
 BUILD_TARGET="aarch64-unknown-linux-${CH_LIBC}"

scripts/run_integration_tests_x86_64.sh

@@ -189,9 +189,9 @@ sudo ip tuntap add vfio-tap3 mode tap
 sudo ip link set vfio-tap3 master vfio-br0
 sudo ip link set vfio-tap3 up
 
-# Create tap interface without multipe queues support for vhost_user_net test.
+# Create tap interface without multiple queues support for vhost_user_net test.
 sudo ip tuntap add name vunet-tap0 mode tap
-# Create tap interface with multipe queues support for vhost_user_net test.
+# Create tap interface with multiple queues support for vhost_user_net test.
 sudo ip tuntap add name vunet-tap1 mode tap multi_queue
 
 BUILD_TARGET="$(uname -m)-unknown-linux-${CH_LIBC}"

vhost_user_fs/src/filesystem.rs

@@ -763,7 +763,7 @@ pub trait FileSystem {
 
     /// Allocate requested space for file data.
     ///
-    /// If this function returns success, then the file sytem must guarantee that it is possible to
+    /// If this function returns success, then the file system must guarantee that it is possible to
     /// write up to `length` bytes of data starting at `offset` without failing due to a lack of
     /// free space on the disk.
     ///

virtio-devices/src/iommu.rs

@@ -809,7 +809,7 @@ impl Iommu {
     // virtual IOMMU. This list is translated into a virtio-iommu configuration
     // topology, so that it can be understood by the guest driver.
     //
-    // The topology is overriden everytime this function is being invoked.
+    // The topology is overridden everytime this function is being invoked.
     //
     // This function is dedicated to PCI, which means it will exclusively
     // create VIRTIO_IOMMU_TOPO_PCI_RANGE entries.

virtio-devices/src/mem.rs

@@ -66,7 +66,7 @@ const VIRTIO_MEM_RESP_NACK: u16 = 1;
 // - VIRTIO_MEM_REQ_UNPLUG_ALL
 // VIRTIO_MEM_RESP_BUSY: u16 = 2;
 
-// Error in request (e.g. addresses/alignemnt), applicable for
+// Error in request (e.g. addresses/alignment), applicable for
 // - VIRTIO_MEM_REQ_PLUG
 // - VIRTIO_MEM_REQ_UNPLUG
 // - VIRTIO_MEM_REQ_STATE
@@ -664,7 +664,7 @@ impl EpollHelperHandler for MemEpollHandler {
                         },
                     };
                     if let Err(e) = self.resize.send(r) {
-                        error!("Sending \"resize\" reponse: {:?}", e);
+                        error!("Sending \"resize\" response: {:?}", e);
                         return true;
                     }
                     if signal_error {

virtio-devices/src/net_util.rs

@@ -82,7 +82,7 @@ pub enum Error {
     InvalidQueuePairsNum,
     /// No memory passed in.
     NoMemory,
-    /// No ueue pairs nummber.
+    /// No ueue pairs number.
     NoQueuePairsNum,
 }
 

virtio-devices/src/vsock/csm/connection.rs

@@ -235,7 +235,7 @@ where
                 }
                 Err(err) if err.kind() == ErrorKind::WouldBlock => {
                     // This shouldn't actually happen (receiving EWOULDBLOCK after EPOLLIN), but
-                    // apparently it does, so we need to handle it greacefully.
+                    // apparently it does, so we need to handle it gracefully.
                     warn!(
                         "vsock: unexpected EWOULDBLOCK while reading from backing stream: \
                          lp={}, pp={}, err={:?}",
@@ -905,7 +905,7 @@ mod tests {
         let mut ctx = CsmTestContext::new(ConnState::PeerInit);
         assert!(ctx.conn.has_pending_rx());
         ctx.recv();
-        // For peer-initiated requests, our connection should always yield a vsock reponse packet,
+        // For peer-initiated requests, our connection should always yield a vsock response packet,
         // in order to establish the connection.
         assert_eq!(ctx.pkt.op(), uapi::VSOCK_OP_RESPONSE);
         assert_eq!(ctx.pkt.src_cid(), LOCAL_CID);
@@ -1165,7 +1165,7 @@ mod tests {
                 .contains(epoll::Events::EPOLLOUT));
             assert_eq!(ctx.conn.tx_buf.len(), data.len());
 
-            // Unlock the write stream and notify the connection it can now write its bufferred
+            // Unlock the write stream and notify the connection it can now write its buffered
             // data.
             ctx.set_stream(TestStream::new());
             ctx.conn.notify(epoll::Events::EPOLLOUT);

virtio-devices/src/vsock/csm/txbuf.rs

@@ -65,7 +65,7 @@ impl TxBuf {
         let data = self.data.get_or_insert_with(||
                 // Using uninitialized memory here is quite safe, since we never read from any
                 // area of the buffer before writing to it. First we push, then we flush only
-                // what had been prviously pushed.
+                // what had been previously pushed.
                 Box::new(unsafe {mem::MaybeUninit::<[u8; Self::SIZE]>::uninit().assume_init()}));
 
         // Buffer head, as an offset into the data slice.

virtio-devices/src/vsock/device.rs

@@ -19,7 +19,7 @@ use crate::{
 };
 use anyhow::anyhow;
 /// This is the `VirtioDevice` implementation for our vsock device. It handles the virtio-level
-/// device logic: feature negociation, device configuration, and device activation.
+/// device logic: feature negotiation, device configuration, and device activation.
 /// The run-time device logic (i.e. event-driven data handling) is implemented by
 /// `super::epoll_handler::EpollHandler`.
 ///
@@ -272,7 +272,7 @@ where
                 // After the backend has been kicked, it might've freed up some resources, so we
                 // can attempt to send it more data to process.
                 // In particular, if `self.backend.send_pkt()` halted the TX queue processing (by
-                // reurning an error) at some point in the past, now is the time to try walking the
+                // returning an error) at some point in the past, now is the time to try walking the
                 // TX queue again.
                 if let Err(e) = self.process_tx() {
                     error!("Failed to process TX queue: {:?}", e);

virtio-devices/src/vsock/packet.rs

@@ -70,7 +70,7 @@ const HDROFF_TYPE: usize = 28;
 // Operation ID - one of the VSOCK_OP_* values; e.g.
 // - VSOCK_OP_RW: a data packet;
 // - VSOCK_OP_REQUEST: connection request;
-// - VSOCK_OP_RST: forcefull connection termination;
+// - VSOCK_OP_RST: forceful connection termination;
 // etc (see `super::defs::uapi` for the full list).
 const HDROFF_OP: usize = 30;
 

virtio-devices/src/vsock/unix/muxer.rs

@@ -120,7 +120,7 @@ pub struct VsockMuxer {
 impl VsockChannel for VsockMuxer {
     /// Deliver a vsock packet to the guest vsock driver.
     ///
-    /// Retuns:
+    /// Returns:
     /// - `Ok(())`: `pkt` has been successfully filled in; or
     /// - `Err(VsockError::NoData)`: there was no available data with which to fill in the
     ///   packet.
@@ -280,13 +280,13 @@ impl VsockEpollListener for VsockMuxer {
     /// Get the epoll events to be polled upstream.
     ///
     /// Since the polled FD is a nested epoll FD, we're only interested in EPOLLIN events (i.e.
-    /// some event occured on one of the FDs registered under our epoll FD).
+    /// some event occurred on one of the FDs registered under our epoll FD).
     ///
     fn get_polled_evset(&self) -> epoll::Events {
         epoll::Events::EPOLLIN
     }
 
-    /// Notify the muxer about a pending event having occured under its nested epoll FD.
+    /// Notify the muxer about a pending event having occurred under its nested epoll FD.
     ///
     fn notify(&mut self, _: epoll::Events) {
         debug!("vsock: muxer received kick");
@@ -376,7 +376,7 @@ impl VsockMuxer {
                 let key_copy = *key;
                 let evset_copy = *evset;
                 // The handling of this event will most probably mutate the state of the
-                // receiving conection. We'll need to check for new pending RX, event set
+                // receiving connection. We'll need to check for new pending RX, event set
                 // mutation, and all that, so we're wrapping the event delivery inside those
                 // checks.
                 self.apply_conn_mutation(key_copy, |conn| {
@@ -608,7 +608,7 @@ impl VsockMuxer {
     ///
     fn allocate_local_port(&mut self) -> u32 {
         // TODO: this doesn't seem very space-efficient.
-        // Mybe rewrite this to limit port range and use a bitmap?
+        // Maybe rewrite this to limit port range and use a bitmap?
         //
 
         loop {
@@ -626,10 +626,10 @@ impl VsockMuxer {
         self.local_port_set.remove(&port);
     }
 
-    /// Handle a new connection request comming from our peer (the guest vsock driver).
+    /// Handle a new connection request coming from our peer (the guest vsock driver).
     ///
     /// This will attempt to connect to a host-side Unix socket, expected to be listening at
-    /// the file system path corresponing to the destination port. If successful, a new
+    /// the file system path corresponding to the destination port. If successful, a new
     /// connection object will be created and added to the connection pool. On failure, a new
     /// RST packet will be scheduled for delivery to the guest.
     ///
@@ -1232,7 +1232,7 @@ mod tests {
             streams.push(listener.accept());
         }
 
-        // The muxer RX queue should now be full (with connection reponses), but still
+        // The muxer RX queue should now be full (with connection responses), but still
         // synchronized.
         assert!(ctx.muxer.rxq.is_synced());
 

vm-device/src/lib.rs

@@ -19,7 +19,7 @@ pub enum Error {
     IoError(io::Error),
 }
 
-/// Type of Message Singaled Interrupt
+/// Type of Message Signalled Interrupt
 #[derive(Copy, Clone, Debug, PartialEq, Serialize, Deserialize)]
 pub enum MsiIrqType {
     /// PCI MSI IRQ numbers.

vm-virtio/src/queue.rs

@@ -86,7 +86,7 @@ impl<'a> Iterator for DescIter<'a> {
     }
 }
 
-/// A virtio descriptor constraints with C representive.
+/// A virtio descriptor constraints with C representative.
 #[repr(C)]
 #[derive(Default, Clone, Copy)]
 pub struct Descriptor {
@@ -540,13 +540,13 @@ impl Queue {
             );
             false
         } else if desc_table.mask(0xf) != 0 {
-            error!("virtio queue descriptor table breaks alignment contraints");
+            error!("virtio queue descriptor table breaks alignment constraints");
             false
         } else if avail_ring.mask(0x1) != 0 {
-            error!("virtio queue available ring breaks alignment contraints");
+            error!("virtio queue available ring breaks alignment constraints");
             false
         } else if used_ring.mask(0x3) != 0 {
-            error!("virtio queue used ring breaks alignment contraints");
+            error!("virtio queue used ring breaks alignment constraints");
             false
         } else {
             true

vmm/src/api/mod.rs

@@ -55,7 +55,7 @@ pub enum ApiError {
     /// API request send error
     RequestSend(SendError<ApiRequest>),
 
-    /// Wrong reponse payload type
+    /// Wrong response payload type
     ResponsePayloadType,
 
     /// API response receive error

vmm/src/config.rs

@@ -32,7 +32,7 @@ pub enum Error {
     ParseFsSockMissing,
     /// Cannot have dax=off along with cache_size parameter.
     InvalidCacheSizeWithDaxOff,
-    /// Missing persistant memory file parameter.
+    /// Missing persistent memory file parameter.
     ParsePmemFileMissing,
     /// Missing vsock socket path parameter.
     ParseVsockSockMissing,
@@ -56,7 +56,7 @@ pub enum Error {
     ParseRNG(OptionParserError),
     /// Error parsing filesystem parameters
     ParseFileSystem(OptionParserError),
-    /// Error parsing persistent memorry parameters
+    /// Error parsing persistent memory parameters
     ParsePersistentMemory(OptionParserError),
     /// Failed parsing console
     ParseConsole(OptionParserError),

vmm/src/memory_manager.rs

@@ -250,7 +250,7 @@ const LENGTH_OFFSET_HIGH: u64 = 0xC;
 const STATUS_OFFSET: u64 = 0x14;
 const SELECTION_OFFSET: u64 = 0;
 
-// The MMIO address space size is substracted with the size of a 4k page. This
+// The MMIO address space size is subtracted with the size of a 4k page. This
 // is done on purpose to workaround a Linux bug when the VMM allocates devices
 // at the end of the addressable space.
 fn mmio_address_space_size() -> u64 {