diff options
| -rw-r--r-- | content.tex | 14 |
1 files changed, 13 insertions, 1 deletions
diff --git a/content.tex b/content.tex index ef10cc0..56fe7ac 100644 --- a/content.tex +++ b/content.tex @@ -3941,7 +3941,7 @@ struct virtio_blk_req { le32 type; le32 reserved; le64 sector; - u8 data[][512]; + u8 data[]; u8 status; }; @@ -3971,6 +3971,11 @@ The \field{sector} number indicates the offset (multiplied by 512) where the read or write is to occur. This field is unused and set to 0 for commands other than read or write. +VIRTIO_BLK_T_IN requests populate \field{data} with the contents of sectors +read from the block device (in multiples of 512 bytes). VIRTIO_BLK_T_OUT +requests write the contents of \field{data} to the block device (in multiples +of 512 bytes). + The \field{data} used for discard or write zeroes command is described by one or more virtio_blk_discard_write_zeroes structs. \field{sector} indicates the starting offset (in 512-byte units) of the segment, while @@ -3997,6 +4002,13 @@ A driver SHOULD accept the VIRTIO_BLK_F_RO feature if offered. A driver MUST set \field{sector} to 0 for a VIRTIO_BLK_T_FLUSH request. A driver SHOULD NOT include any data in a VIRTIO_BLK_T_FLUSH request. +The length of \field{data} MUST be a multiple of 512 bytes for VIRTIO_BLK_T_IN +and VIRTIO_BLK_T_OUT requests. + +The length of \field{data} MUST be a multiple of the size of struct +virtio_blk_discard_write_zeroes for VIRTIO_BLK_T_DISCARD and +VIRTIO_BLK_T_WRITE_ZEROES requests. + If the VIRTIO_BLK_F_CONFIG_WCE feature is negotiated, the driver MAY switch to writethrough or writeback mode by writing respectively 0 and 1 to the \field{writeback} field. After writing a 0 to \field{writeback}, |