[8333] in linux-scsi channel archive
Re: Problem
daemon@ATHENA.MIT.EDU (Eric Youngdale)
Thu Mar 9 11:49:59 2000
Message-ID: <007601bf89e2$c7ee9860$4d0310ac@fairfax.datafocus.com>
From: "Eric Youngdale" <eric@andante.org>
To: <mjacob@feral.com>, <sjbuller@us.ibm.com>,
"Eric Lee Green" <eric@estinc.com>
Cc: <linux-scsi@vger.rutgers.edu>
Date: Thu, 9 Mar 2000 11:16:09 -0500
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> In terms of lun support- this is, as of 2.2.14 for sure- a property of the
> HBA merged with a partially kernel configurable and certainly patchable
and
> eddittable value in scsi.c (max_scsi_luns). In fact, the max_luns property
in
> the host adapter structure is an unsigned int. There is a problem that the
> arguments to scan_scsis are unsigned char, which puts Linux on par with
the
> non-NDI framework Solaris, but this is so trivial a fix that it's hardly
worth
> discussing.
But worth mentioning - I can fix this the next time I am in the code,
and we won't have to worry about it any longer. No point in allowing these
silly little things to stand in the way of progress.
> In terms of adding extra devs- this is a quantity only pertinent
> for allocating extra space for loadable HBA rescans- this doesn't have
> anything to do with boot time probing with static linking, or if it does,
you
> can always change the SD_EXTRA_DEVS to something reasonable (like 512).
We still have an effective limit of 128 disks. 8 majors * 16
disks/major.
Now that devfs is in, I am wondering whether it would make sense to
allow the disk driver to dynamically allocate as many majors as it needs
above and beyond the 8 majors. All of the hardcoded assumptions about major
numbers should be gone from ll_rw_blk.c. In there would be the nasty problem
of somehow getting the /dev tree - with devfs, that becomes a non-issue as
the /dev entries are automatically created.
There is still a limit of 256 majors * 16 disks/major or 4096 disks (an
over-estimate as some majors are unavailable). We won't worry about that
for now... :-).
-Eric
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