console: the VM's console is a userland driver's, and the UART goes quiet while it carries the log

Cargo.toml

@@ -25,12 +25,12 @@ members = [
     "build/root",
     "kernel",
     "kernel/amdvi",
-    "kernel/dma",
     "kernel/gicv3",
     "kernel/its",
     "kernel/loom",
     "kernel/pci",
     "kernel/phys",
+    "kernel/register",
     "kernel/sim",
     "kernel/smmu",
     "lib/acpi",
@@ -77,6 +77,8 @@ members = [
     "lib/userbound",
     "lib/vdagent",
     "lib/virtio",
+    "lib/virtio-serial",
+    "lib/virtio-serial/claim",
     "lib/wallclock",
     "loader",
     "sdk/abi",
@@ -141,6 +143,7 @@ members = [
     "system/usbd",
     "system/usbd/xhci",
     "system/vdagent",
+    "system/virtio-console",
     "system/vdagent/bridge",
     "tests/guest/hangupholder",
     "tests/guest/kernelprobe",
@@ -254,6 +257,7 @@ toyos-session = { path = "lib/session" }
 # QEMU's clipboard channel's port name, id and port count, so the launch reads
 # the declaration the guest's agent drives.
 toyos-vdagent = { path = "lib/vdagent" }
+toyos-virtio-serial = { path = "lib/virtio-serial" }
 # The watchdog's parameter name, so the gate over `kernel/src/params.rs` reads
 # the same constant the kernel and the bootloader do.
 toyos-tco = { path = "lib/tco" }

build/build.rs

@@ -653,7 +653,8 @@ const SUPERVISOR_SERVED: &[&str] = &[toyos_swap::PORT, "power", toyos_manifest::
 /// clipboard port, whose holder is sent every copy made in the session, the
 /// display port, whose holder sets the mode and the scale every window is
 /// drawn at, and the session-admin port, whose holder signs its user's
-/// sessions out.
+/// sessions out, and the log's carrier port, for whose holder the console
+/// UART goes quiet.
 const HELD_ALONE: &[(&str, &[&str])] = &[
     (toyos_swap::PORT, &[toyos_swap::HOLDER]),
     (toyos_manifest::grants::PORT, &[toyos_manifest::grants::HOLDER]),
@@ -662,6 +663,7 @@ const HELD_ALONE: &[(&str, &[&str])] = &[
     (toyos_manifest::clipboard::PORT, &[toyos_manifest::clipboard::HOLDER]),
     (toyos_manifest::display::PORT, &[toyos_manifest::display::HOLDER]),
     (toyos_session::ADMIN_PORT, &[toyos_session::ADMIN_HOLDER]),
+    (toyos_logstream::CARRIER, &[toyos_logstream::CARRIER_HOLDER]),
 ];
 
 /// Rows, as a refusal names them.
@@ -3290,6 +3292,10 @@ mod tests {
         assert!(held_by_their_holders_alone(&vdagent).is_ok());
         let editor: SystemConfig = toml::from_str("[programs.editor]\nreceives = [\"clipboard\"]\n").unwrap();
         assert!(held_by_their_holders_alone(&editor).is_err());
+        let console: SystemConfig = toml::from_str("[programs.virtio-console]\nreceives = [\"log-carrier\"]\n").unwrap();
+        assert!(held_by_their_holders_alone(&console).is_ok());
+        let agent: SystemConfig = toml::from_str("[programs.vdagent]\nreceives = [\"clipboard\", \"log-carrier\"]\n").unwrap();
+        assert!(held_by_their_holders_alone(&agent).unwrap_err().contains("only `virtio-console`"));
     }
 
     /// The prompt port reaches its server alone, and the consent port no row,

build/lib.rs

@@ -25,7 +25,6 @@ pub mod flags;
 pub mod hostws;
 pub mod identity;
 pub mod image;
-pub mod kernelconsole;
 pub mod signing;
 /// Which kernel containers may be hashed, and by whose keys; read by nothing
 /// but its own tests.
@@ -52,6 +51,7 @@ pub mod tether;
 pub mod toolchain;
 pub mod userlandhost;
 pub mod vdagent;
+pub mod vmconsole;
 pub mod wallpaper;
 
 use std::path::{Path, PathBuf};

build/qemu.rs

@@ -52,7 +52,7 @@ use std::path::PathBuf;
 use std::process::{Command, Stdio};
 
 use toyos_build::arch::{Accel, Arch};
-use toyos_build::kernelconsole;
+use toyos_build::vmconsole;
 
 /// The hardware shape QEMU presents to the guest.
 ///
@@ -61,7 +61,7 @@ use toyos_build::kernelconsole;
 /// virtio device, which changes the console, the network, and audio too.
 #[derive(Clone, Copy, PartialEq)]
 pub enum Profile {
-    /// virtio-gpu for the display, virtio-console for the console, plus
+    /// virtio-gpu for the display, a virtio-serial port for the console, plus
     /// virtio-net and virtio-sound.
     Virtio,
     /// `-vga std`, so firmware publishes a GOP and the kernel takes the
@@ -256,24 +256,17 @@ pub fn launch(opts: &Options) {
         qemu.arg("-device")
             .arg(format!("virtio-sound-pci,audiodev=audio0,streams=1{platform}"));
 
-        // The clipboard's channel, just before the console's function, so it
-        // enumerates first and the kernel's console rule runs.
         qemu.args(toyos_build::vdagent::args(platform));
 
-        // Console wiring: virtio-console on stdio is the primary I/O channel
-        // (the kernel switches to it once virtio-console init completes —
-        // see drivers/virtio_console.rs). UART stays on a file so early-boot
-        // logs (before virtio is up) and panic fallback are still captured.
+        // The console's port on stdio, where `/system/bin/virtio-console`
+        // carries the log once userland runs; the UART on a file, which keeps
+        // the loader, the early boot, the stop and a fatal path's report, and
+        // the whole log again if the console's carrier goes.
         qemu.arg("-serial")
             .arg("file:/tmp/toyos-uart-early.log")
             .arg("-chardev")
             .arg("stdio,id=cs0,signal=off")
-            .arg("-device")
-            .arg(format!(
-                "virtio-serial-pci-non-transitional,id=virtio-serial0,max_ports=1{platform}"
-            ))
-            .arg("-device")
-            .arg("virtconsole,chardev=cs0,id=console0");
+            .args(toyos_build::vmconsole::args("cs0", platform));
     } else if opts.mute {
         eprintln!("metal-sim: no 16550 — the framebuffer is the only channel out");
         qemu.arg("-serial").arg("none");
@@ -320,7 +313,7 @@ pub fn launch(opts: &Options) {
     let console = child.stdout.take().expect("QEMU's stdout is piped");
     // The console ends when QEMU does; a relay that fails first ends QEMU, which
     // would otherwise run on into a pipe nobody reads.
-    if let Err(relay) = kernelconsole::relay(console, &mut terminal) {
+    if let Err(relay) = vmconsole::relay(console, &mut terminal) {
         // SIGTERM, not `Child::kill`'s SIGKILL: QEMU gives the terminal back its
         // modes only on its own exit path.
         let pid = libc::pid_t::try_from(child.id()).expect("a pid is a pid_t");

build/sourcegate.rs

@@ -88,18 +88,15 @@ const LOG_PRODUCERS: &[&str] = &["log!(", "alert!(", "boot_phase!(", "log::emit(
 const NMI_SILENT: &[&str] =
     &["kernel/src/arch/x86_64/idt/nmi.rs", "kernel/src/hardlockup/mod.rs"];
 
-/// Every `enable_bus_master(` site `kernel/src` holds, by file and count.
-/// No kernel site leaves a device it declined mastering the bus: virtio
-/// parses its capability chain first, and switches mastering off on a refusal
-/// that comes after arming.
+/// Every `enable_bus_master(` site `kernel/src` holds, by file and count:
+/// its definition, and the AMD-Vi unit's own function.
 ///
 /// A function handed to a *process* takes the other path: `pcidev` arms bus
 /// mastering with `start_bus_mastering`, after the address space that bounds it
 /// exists, so `enable_bus_master` stays what a kernel driver calls and the
 /// count below stays the census of drivers this kernel has.
 const BUS_MASTER_SITES: &[(&str, usize)] = &[
     ("kernel/src/drivers/pci.rs", 1),
-    ("kernel/src/drivers/virtio.rs", 1),
     ("kernel/src/arch/x86_64/amdvi/mod.rs", 1),
 ];
 
@@ -137,7 +134,6 @@ const SENTINEL_ALLOWED: &[(&str, usize)] = &[
 /// reds beside a permitted one and a deleted one reds its own stale row.
 const AUTO_TRAIT_IMPLS: &[(&str, usize)] = &[
     ("kernel/src/drivers/panic_console/mod.rs", 3),
-    ("kernel/src/drivers/virtio_console.rs", 1),
     ("kernel/src/arch/x86_64/hw.rs", 1),
     ("kernel/src/mm/mmio.rs", 2),
     ("kernel/src/mm/region.rs", 2),

build/vdagent.rs

@@ -1,11 +1,7 @@
 //! QEMU's clipboard channel at the launch: its `qemu-vdagent` chardev, the
 //! virtio-serial function of its own it is on, and the agent's port, from the
-//! one declaration the guest's agent reads (`toyos-vdagent`).
-//!
-//! **A function of its own**, created just before the console's: the console's
-//! function is the kernel's log channel from early boot, and the agent's
-//! enumerates first, so every virtio boot runs the kernel's choice of console
-//! (`toyos_pci::console`).
+//! declarations the guest's agent reads (`toyos-vdagent`,
+//! `toyos-virtio-serial`).
 //!
 //! **The chardev exists only in a QEMU built with spice-protocol** (QEMU's
 //! `qapi/char.json`, `'if': 'CONFIG_SPICE_PROTOCOL'`), so a launch asks QEMU
@@ -14,7 +10,8 @@
 use std::process::Command;
 use std::sync::OnceLock;
 
-use toyos_vdagent::{MAX_PORTS, PORT_ID, PORT_NAME};
+use toyos_vdagent::PORT_NAME;
+use toyos_virtio_serial::{MAX_PORTS, PORT_ID};
 
 use crate::arch::Arch;