On Tue, 2019-01-22 at 15:47 -0500, Douglas Gilbert wrote:
> On 2019-01-22 1:25 p.m., Bart Van Assche wrote:
> > The default behavior of the SCSI core is to set the block layer request
> > queue parameter max_segment_size to 64 KB. That means that elements of
> > scatterlists are limited to 64 KB. Since RDMA adapters support larger
> > sizes, increase max_segment_size for the SRP initiator.
> >
> > Notes:
> > - The SCSI max_segment_size parameter was introduced in kernel v5.0. See
> > also commit 50c2e9107f17 ("scsi: introduce a max_segment_size
> > host_template parameters").
> > - Some other block drivers already set max_segment_size to UINT_MAX,
> > e.g. nbd and rbd.
>
> In my sg v4 driver rewrite one of options within the SG_SET_GET_EXTENDED
> ioctl is to allow the user to modify this value. It is a #define to
> 32 KB in the production sg v3 driver.
Hi Doug,
This functionality seems useful to me. But it is not clear to me how it
will be guaranteed that the value set by the user won't exceed the largest
max_segment_size value supported by the driver?
Thanks,
Bart.
