Why doesn't rtems_blkdev_sg_buffer have next pointer?

[Sebastian Huber]

For an SD/MMC driver you should operate at this level since this is 
covered by "freebsd/sys/dev/mmc/mmcsd.c".

On 18/06/15 14:16, Chan Kim wrote:
> Hi all,
>
> I have a basic question.
> in rtems 4.10.99 version, I see in cpukit/libblock/include/rtems/blkdev.h,
> -------------------------------------
> typedef struct rtems_blkdev_sg_buffer {
> rtems_blkdev_bnum block;             // this seems to be the start block number of this access
> uint32_t length;
> void *buffer;
> void *user;
> } rtems_blkdev_sg_buffer;
>
> typedef struct rtems_blkdev_request {
>    rtems_blkdev_request_op req;
>    rtems_blkdev_request_cb done;
>    void *done_arg;
>    rtems_status_code status;
>    uint32_t bufnum;                       // this seems to be # of blocks
>    rtems_id io_task;
>    rtems_blkdev_sg_buffer        bufs[0];
> } rtems_blkdev_request;
> ---------------------------------------
>
> the rtems_blkdev_request has only a single entry of rtems_blkdev_sg_buffer. But usually scatter-list uses next pointer to link buffers in host memory together. But in rtems, why isn't there such link field? Does the block device request I/O with only a single buffer always?
> Could somebody please answer to this question?
> regards,
>
> Chan Kim
> _______________________________________________
> users mailing list
> users at rtems.org
> http://lists.rtems.org/mailman/listinfo/users

-- 
Sebastian Huber, embedded brains GmbH

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