base: re-sync ACPI userspace with upstream master

Phase B of the ACPI fork-sync plan (local/docs/ACPI-FORK-SYNC-STRATEGY-2026-06-30.md).
Pairs with the kernel fork-sync commit 4f2a043.

Restores the base fork to match upstream Redox OS base master for the
ACPI userspace:

- Cargo.toml (workspace):
  * Add acpi = { git = "...redox-os/acpi.git", branch = "redox-6.x" }
    workspace dependency. The jackpot51/acpi GitHub fork was
    deprecated in favor of the gitlab.redox-os.org fork that
    tracks the redox-6.x branch (has AcpiVerb-style AML updates,
    PIIX4 fixes, VirtualBox boot fix per upstream MR #243).
  * Switch redox_syscall from crates.io 0.8.1 to a git ref of
    gitlab.redox-os.org/redox-os/syscall.git, with [patch.crates-io]
    redirecting crates.io consumers to the gitlab fork. The
    crates.io 0.8.1 release predates AcpiVerb (commit 79cb6d9)
    that the kernel MR #613 / base MR #275 introduce.

- drivers/acpid/Cargo.toml: acpi.workspace = true.

- drivers/amlserde/Cargo.toml: acpi.workspace = true.

- drivers/hwd/Cargo.toml: add redox_syscall.workspace = true
  dependency. HWD now needs the AcpiVerb enum to construct Fd-based
  calls into the kernel ACPI scheme.

- drivers/amlserde/src/lib.rs: split AmlSerdeReferenceKind::LocalOrArg
  into 4 separate variants matching the new gitlab acpi crate
  ReferenceKind enum:
    Local, Arg, Index, Named
  Required by upstream commit "Update ACPI crate" (f2f834d4).

- drivers/acpid/src/main.rs: rewrite the RXSDT and kstop acquisition
  to use the new Fd::open + call_ro(AcpiVerb::*) interface:
    kernel_acpi_handle = Fd::open("/scheme/kernel.acpi", O_CLOEXEC, 0)
    rxsdt = kernel_acpi_handle.call_ro(buf, READ, &[ReadRxsdt])
    shutdown_pipe = kernel_acpi_handle.openat("kstop", O_CLOEXEC, 0)
  Also fixes the nsmgr deadlock by moving setrens(0, 0) BEFORE
  daemon.ready() (upstream commit 9dd6901d).

- drivers/hwd/src/backend/acpi.rs: rewrite AcpiBackend::new() to use
  the new Fd::open + call_ro(AcpiVerb::ReadRxsdt) interface, matching
  the kernel ACPI scheme rewrite.

Verified by: CI=1 ./local/scripts/build-redbear.sh redbear-mini
succeeded with exit 0, producing build/x86_64/redbear-mini.iso
(512 MB) at 2026-06-30 04:54.

drivers/acpid/Cargo.toml

@@ -8,7 +8,7 @@ edition = "2018"
 # See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
 
 [dependencies]
-acpi = { git = "https://github.com/jackpot51/acpi.git" }
+acpi.workspace = true
 arrayvec = "0.7.6"
 log.workspace = true
 num-derive = "0.3"

drivers/acpid/src/main.rs

@@ -1,14 +1,14 @@
 use std::convert::TryFrom;
-use std::fs::File;
 use std::mem;
 use std::ops::ControlFlow;
-use std::os::unix::io::AsRawFd;
 use std::sync::Arc;
 
 use ::acpi::aml::op_region::{RegionHandler, RegionSpace};
 use event::{EventFlags, RawEventQueue};
+use libredox::Fd;
 use redox_scheme::{scheme::register_sync_scheme, Socket};
 use scheme_utils::Blocking;
+use syscall::flag::{AcpiVerb, CallFlags};
 
 mod acpi;
 mod aml_physmem;
@@ -29,9 +29,19 @@ fn daemon(daemon: daemon::Daemon) -> ! {
 
     log::info!("acpid start");
 
-    let rxsdt_raw_data: Arc<[u8]> = std::fs::read("/scheme/kernel.acpi/rxsdt")
-        .expect("acpid: failed to read `/scheme/kernel.acpi/rxsdt`")
-        .into();
+    let kernel_acpi_handle = Fd::open("/scheme/kernel.acpi", libredox::flag::O_CLOEXEC, 0)
+        .expect("acpid: failed to open kernel ACPI handle");
+
+    let rxsdt_raw_data: Arc<[u8]> = {
+        let len = kernel_acpi_handle
+            .call_ro(&mut [], CallFlags::READ, &[AcpiVerb::ReadRxsdt as u64])
+            .expect("acpid: failed to get rxsdt length");
+        let mut buf = vec![0_u8; len];
+        kernel_acpi_handle
+            .call_ro(&mut buf, CallFlags::READ, &[AcpiVerb::ReadRxsdt as u64])
+            .expect("acpid: failed to read rxsdt");
+        buf.into()
+    };
 
     if rxsdt_raw_data.is_empty() {
         log::info!("System doesn't use ACPI");
@@ -78,8 +88,9 @@ fn daemon(daemon: daemon::Daemon) -> ! {
     #[cfg(any(target_arch = "x86", target_arch = "x86_64"))]
     common::acquire_port_io_rights().expect("acpid: failed to set I/O privilege level to Ring 3");
 
-    let shutdown_pipe = File::open("/scheme/kernel.acpi/kstop")
-        .expect("acpid: failed to open `/scheme/kernel.acpi/kstop`");
+    let shutdown_pipe = kernel_acpi_handle
+        .openat("kstop", libredox::flag::O_CLOEXEC, 0)
+        .expect("acpid: failed to open kstop handle");
 
     let mut event_queue = RawEventQueue::new().expect("acpid: failed to create event queue");
     let socket = Socket::nonblock().expect("acpid: failed to create disk scheme");
@@ -88,7 +99,7 @@ fn daemon(daemon: daemon::Daemon) -> ! {
     let mut handler = Blocking::new(&socket, 16);
 
     event_queue
-        .subscribe(shutdown_pipe.as_raw_fd() as usize, 0, EventFlags::READ)
+        .subscribe(shutdown_pipe.raw() as usize, 0, EventFlags::READ)
         .expect("acpid: failed to register shutdown pipe for event queue");
     event_queue
         .subscribe(socket.inner().raw(), 1, EventFlags::READ)
@@ -97,10 +108,10 @@ fn daemon(daemon: daemon::Daemon) -> ! {
     register_sync_scheme(&socket, "acpi", &mut scheme)
         .expect("acpid: failed to register acpi scheme to namespace");
 
-    daemon.ready();
-
     libredox::call::setrens(0, 0).expect("acpid: failed to enter null namespace");
 
+    daemon.ready();
+
     let mut mounted = true;
     while mounted {
         let Some(event) = event_queue
@@ -121,7 +132,7 @@ fn daemon(daemon: daemon::Daemon) -> ! {
                     ControlFlow::Break(()) => break,
                 }
             }
-        } else if event.fd == shutdown_pipe.as_raw_fd() as usize {
+        } else if event.fd == shutdown_pipe.raw() as usize {
             log::info!("Received shutdown request from kernel.");
             mounted = false;
         } else {
@@ -141,4 +152,4 @@ fn daemon(daemon: daemon::Daemon) -> ! {
 fn main() {
     common::init();
     daemon::Daemon::new(daemon);
-}
+}