The branch main has been updated by tuexen: URL: https://cgit.FreeBSD.org/src/commit/?id=c70755bc0d8f703dbaa1520c15e8213a95847dd5
commit c70755bc0d8f703dbaa1520c15e8213a95847dd5 Author: Timo Völker <[email protected]> AuthorDate: 2026-03-02 18:15:37 +0000 Commit: Michael Tuexen <[email protected]> CommitDate: 2026-03-02 18:15:37 +0000 virtio: add loader tunables to sysctl virtio_pci uses two loader tunables that should be more visible. This patch adds these loader tunables to sysctl and describes them in the virtio(4) man page. Reviewed by: imp (erlier version), tuexen MFC after: 1 week Differential Revision: https://reviews.freebsd.org/D55533 --- share/man/man4/virtio.4 | 28 ++++++++++++++++++++++++++-- sys/dev/virtio/pci/virtio_pci.c | 7 ++++++- sys/dev/virtio/pci/virtio_pci_modern.c | 7 ++++++- sys/dev/virtio/virtio.c | 4 ++++ 4 files changed, 42 insertions(+), 4 deletions(-) diff --git a/share/man/man4/virtio.4 b/share/man/man4/virtio.4 index 1e5ea0e4a7da..0598d5d8621d 100644 --- a/share/man/man4/virtio.4 +++ b/share/man/man4/virtio.4 @@ -22,7 +22,7 @@ .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF .\" SUCH DAMAGE. .\" -.Dd May 26, 2019 +.Dd March 2, 2026 .Dt VIRTIO 4 .Os .Sh NAME @@ -54,7 +54,7 @@ The .Nm module provides a shared memory transport called a virtqueue. The -.Xr virtio_pci +.Sy virtio_pci device driver represents an emulated PCI device that the hypervisor makes available to the VM. This device provides the probing, configuration, and @@ -92,6 +92,30 @@ An emulated SCSI HBA is provided by the .Xr virtio_scsi 4 device driver. .El +.Sh LOADER TUNABLES +Tunables can be set at the +.Xr loader 8 +prompt before booting the kernel or stored in +.Xr loader.conf 5 . +.Bl -tag -width "hw.virtio.pci.transitional" +.It Va hw.virtio.pci.disable_msix +If set to 1, disables MSI-X. +The default value is 0. +.It Va hw.virtio.pci.transitional +For a transitional +.Nm +device, this tunable specifies whether to negotiate +modern mode and use the modern +.Nm +driver +.Pq 1 +or to negotiate legacy mode and +use the legacy +.Nm +driver +.Pq 1 . +The default value is 0. +.El .Sh SEE ALSO .Xr virtio_balloon 4 , .Xr virtio_blk 4 , diff --git a/sys/dev/virtio/pci/virtio_pci.c b/sys/dev/virtio/pci/virtio_pci.c index b7b34b448f6e..2d33d99014ae 100644 --- a/sys/dev/virtio/pci/virtio_pci.c +++ b/sys/dev/virtio/pci/virtio_pci.c @@ -97,8 +97,13 @@ MODULE_VERSION(virtio_pci, 1); MODULE_DEPEND(virtio_pci, pci, 1, 1, 1); MODULE_DEPEND(virtio_pci, virtio, 1, 1, 1); +SYSCTL_DECL(_hw_virtio); +SYSCTL_NODE(_hw_virtio, OID_AUTO, pci, CTLFLAG_RD | CTLFLAG_MPSAFE, 0, + "VirtIO PCI driver parameters"); + int vtpci_disable_msix = 0; -TUNABLE_INT("hw.virtio.pci.disable_msix", &vtpci_disable_msix); +SYSCTL_INT(_hw_virtio_pci, OID_AUTO, disable_msix, CTLFLAG_RDTUN, + &vtpci_disable_msix, 0, "If set to 1, disables MSI-X."); static uint8_t vtpci_read_isr(struct vtpci_common *cn) diff --git a/sys/dev/virtio/pci/virtio_pci_modern.c b/sys/dev/virtio/pci/virtio_pci_modern.c index eb1d5a1e6989..108fd2b5f8e9 100644 --- a/sys/dev/virtio/pci/virtio_pci_modern.c +++ b/sys/dev/virtio/pci/virtio_pci_modern.c @@ -33,6 +33,7 @@ #include <sys/bus.h> #include <sys/lock.h> #include <sys/kernel.h> +#include <sys/sysctl.h> #include <sys/module.h> #include <machine/bus.h> @@ -188,8 +189,12 @@ static void vtpci_modern_write_device_8(struct vtpci_modern_softc *, bus_size_t, uint64_t); /* Tunables. */ +SYSCTL_DECL(_hw_virtio_pci); + static int vtpci_modern_transitional = 0; -TUNABLE_INT("hw.virtio.pci.transitional", &vtpci_modern_transitional); +SYSCTL_INT(_hw_virtio_pci, OID_AUTO, transitional, CTLFLAG_RDTUN, + &vtpci_modern_transitional, 0, + "If 0, a transitional VirtIO device is used in legacy mode; otherwise, in modern mode."); static device_method_t vtpci_modern_methods[] = { /* Device interface. */ diff --git a/sys/dev/virtio/virtio.c b/sys/dev/virtio/virtio.c index 75d65ba4a8c8..be5edcafa7ff 100644 --- a/sys/dev/virtio/virtio.c +++ b/sys/dev/virtio/virtio.c @@ -30,6 +30,7 @@ #include <sys/systm.h> #include <sys/kernel.h> #include <sys/malloc.h> +#include <sys/sysctl.h> #include <sys/module.h> #include <sys/sbuf.h> @@ -90,6 +91,9 @@ static struct virtio_feature_desc virtio_common_feature_desc[] = { { 0, NULL } }; +SYSCTL_NODE(_hw, OID_AUTO, virtio, CTLFLAG_RD | CTLFLAG_MPSAFE, 0, + "VirtIO driver parameters"); + const char * virtio_device_name(uint16_t devid) {
