Kernel: Add kernel command line flag to disable VirtIO support

This command line flag can be used to disable VirtIO support on certain configurations (native windows) where interfacing with virtio devices can cause qemu to freeze.
fleximus · Apr 18, 2021 · aaf3d26 · aaf3d26
1 parent 7dc9572
commit aaf3d26
Show file tree

Hide file tree

Showing 4 changed files with 12 additions and 0 deletions.
diff --git a/Documentation/NotesOnWSL.md b/Documentation/NotesOnWSL.md
@@ -40,6 +40,9 @@ By default this will be located at `/mnt/c/Program Files/qemu/qemu-system-i386.e
 
 - Locate the _Windows_ path to the SerenityOS disk image, as native QEMU will be accessing it via the Windows filesystem. If your build tree is located in the WSL2 partition, this will be accessible under the `\\wsl$` network file share (see [notes below](#note-on-filesystems)).
 
+- Set the `SERENITY_KERNEL_CMDLINE` environment variable to disable VirtIO support (Because it is currently broken on native windows QEMU):
+`export SERENITY_KERNEL_CMDLINE="disable_virtio"`
+
 - Set the `SERENITY_DISK_IMAGE` environment variable to the full path of the SerenityOS disk image file from above. For example: \
 `export SERENITY_DISK_IMAGE='\\wsl$\Ubuntu-20.04\home\username\serenity\Build\i686\_disk_image'`
 

diff --git a/Kernel/CommandLine.cpp b/Kernel/CommandLine.cpp
@@ -170,6 +170,11 @@ UNMAP_AFTER_INIT bool CommandLine::disable_uhci_controller() const
  return contains("disable_uhci_controller");
 }
 
+UNMAP_AFTER_INIT bool CommandLine::disable_virtio() const
+{
+ return contains("disable_virtio");
+}
+
 UNMAP_AFTER_INIT AHCIResetMode CommandLine::ahci_reset_mode() const
 {
  const auto ahci_reset_mode = lookup("ahci_reset_mode").value_or("controller");

diff --git a/Kernel/CommandLine.h b/Kernel/CommandLine.h
@@ -87,6 +87,7 @@ class CommandLine {
  [[nodiscard]] bool disable_physical_storage() const;
  [[nodiscard]] bool disable_ps2_controller() const;
  [[nodiscard]] bool disable_uhci_controller() const;
+ [[nodiscard]] bool disable_virtio() const;
  [[nodiscard]] AHCIResetMode ahci_reset_mode() const;
  [[nodiscard]] String userspace_init() const;
  [[nodiscard]] Vector<String> userspace_init_args() const;

diff --git a/Kernel/VirtIO/VirtIO.cpp b/Kernel/VirtIO/VirtIO.cpp
@@ -24,6 +24,7 @@
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
+#include <Kernel/CommandLine.h>
 #include <Kernel/VirtIO/VirtIO.h>
 #include <Kernel/VirtIO/VirtIOConsole.h>
 #include <Kernel/VirtIO/VirtIORNG.h>
@@ -32,6 +33,8 @@ namespace Kernel {
 
 void VirtIO::detect()
 {
+ if (kernel_command_line().disable_virtio())
+ return;
  PCI::enumerate([&](const PCI::Address& address, PCI::ID id) {
  if (address.is_null() || id.is_null())
  return;