diff options
Diffstat (limited to 'virtio-v1.0-wd01-part1-specification.txt')
| -rw-r--r-- | virtio-v1.0-wd01-part1-specification.txt | 14 |
1 files changed, 7 insertions, 7 deletions
diff --git a/virtio-v1.0-wd01-part1-specification.txt b/virtio-v1.0-wd01-part1-specification.txt index f8751ad..d65e8f2 100644 --- a/virtio-v1.0-wd01-part1-specification.txt +++ b/virtio-v1.0-wd01-part1-specification.txt @@ -858,7 +858,7 @@ When used through the legacy interface, the virtio header looks as follows: If MSI-X is enabled for the device, two additional fields -immediately follow this header:[5] +immediately follow this header: +------------++----------------+--------+ @@ -871,6 +871,12 @@ immediately follow this header:[5] | (MSI-X) || Vector | Vector | +------------++----------------+--------+ +Note: When MSI-X capability is enabled, device specific configuration starts at +byte offset 24 in virtio header structure. When MSI-X capability is not +enabled, device specific configuration starts at byte offset 20 in virtio +header. ie. once you enable MSI-X on the device, the other fields move. +If you turn it off again, they move back! + Immediately following these general headers, there may be device-specific headers: @@ -3388,12 +3394,6 @@ the non-PCI implementations (currently lguest and S/390). This is only allowed if the driver does not use any features which would alter this early use of the device. -[5] When MSI-X capability is enabled, device specific configuration starts at -byte offset 24 in virtio header structure. When MSI-X capability is not -enabled, device specific configuration starts at byte offset 20 in virtio -header. ie. once you enable MSI-X on the device, the other fields move. -If you turn it off again, they move back! - [6] The 4096 is based on the x86 page size, but it's also large enough to ensure that the separate parts of the virtqueue are on separate cache lines. |