Commit ac399d8f authored by Michael S. Tsirkin's avatar Michael S. Tsirkin Committed by Rusty Russell
Browse files

virtio_pci: add module param to force legacy mode 



If set, try legacy interface first, modern one if that fails.  Useful to
work around device/driver bugs, and for compatibility testing.

Signed-off-by: default avatarMichael S. Tsirkin <mst@redhat.com>
Signed-off-by: default avatarRusty Russell <rusty@rustcorp.com.au>
parent 46506da5

drivers/virtio/virtio_pci_common.c

+21 −4
Original line number Diff line number Diff line
@@ -19,6 +19,14 @@ 


#include "virtio_pci_common.h"



static bool force_legacy = false;



#if IS_ENABLED(CONFIG_VIRTIO_PCI_LEGACY)

module_param(force_legacy, bool, 0444);

MODULE_PARM_DESC(force_legacy,

		 "Force legacy mode for transitional virtio 1 devices");

#endif



/* wait for pending irq handlers */

void vp_synchronize_vectors(struct virtio_device *vdev)

{
@@ -505,11 +513,20 @@ static int virtio_pci_probe(struct pci_dev *pci_dev, 
	if (rc)

		goto err_request_regions;



	if (force_legacy) {

		rc = virtio_pci_legacy_probe(vp_dev);

		/* Also try modern mode if we can't map BAR0 (no IO space). */

		if (rc == -ENODEV || rc == -ENOMEM)

			rc = virtio_pci_modern_probe(vp_dev);

		if (rc)

			goto err_probe;

	} else {

		rc = virtio_pci_modern_probe(vp_dev);

		if (rc == -ENODEV)

			rc = virtio_pci_legacy_probe(vp_dev);

		if (rc)

			goto err_probe;

	}



	pci_set_master(pci_dev);

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