[6474] in linux-scsi channel archive
Re: Proposal for CONFIG_SCSI_NO_ISA switch
daemon@ATHENA.MIT.EDU (Kurt Garloff)
Thu May 6 17:00:37 1999
Date: Thu, 6 May 1999 20:16:23 +0200
From: Kurt Garloff <garloff@suse.de>
To: Douglas Gilbert <dgilbert@interlog.com>
Cc: linux-scsi@vger.rutgers.edu
Mail-Followup-To: Douglas Gilbert <dgilbert@interlog.com>,
linux-scsi@vger.rutgers.edu
In-Reply-To: <3730F749.B23D8F14@interlog.com>; from Douglas Gilbert on Wed, May 05, 1999 at 09:58:33PM -0400
--GPJrCs/72TxItFYR
Content-Type: text/plain; charset=iso-8859-1
Content-Transfer-Encoding: quoted-printable
On Wed, May 05, 1999 at 09:58:33PM -0400, Douglas Gilbert wrote:
> Proposal
> --------
> The proposal is to add a kernel configuration switch:
> CONFIG_SCSI_NO_ISA [default initially "N"]
>=20
> It would have the following effect when "Y":
> - Any attempt to load an ISA adapter (or more precisely
> "unchecked_isa_dma =3D=3D 1") at boot time or as a module is rejected
> by the SCSI mid-level with an appropriate message to the console,
> log and/or insmod.
> - the SCSI mid-level does _not_ restrict itself below the 16MB level
> when allocating new command blocks or enlarging its buffer pool.
Why not have the mid-level code be intelligent, and only decide at run-time
to try to get mem below 16M (GFP_DMA), if the command is for an adapter with
unchecked_isa_dma=3D=3D1 ??
The buffer pool is shared between the adapters, so it's a little bit hard to
do. So we need a two-class buffer pool:
1. Normal buffers for sane adapters
2. backup buffers (below 16M), which we would use, when
(a) a command is for an ISA adapter
(b) we run out of class 1 buffers
When we run out of class 2 buffers, we allocate more cl.1 or cl.2 buffers,
depending on what adapter caused the running out.
=20
It does not look too difficult. It doesn't make the code more clean, though,
I admit. But cleaning up will be a 2.3 issue ...
I'd prefer this approach, but I'd also agree to have your proposal
implemented.
Regards,
--=20
Kurt Garloff <garloff@suse.de> SuSE GmbH, N=FCrnberg, FRG
Linux kernel development; SCSI driver: DC390 (tmscsim/AM53C974)
--GPJrCs/72TxItFYR
Content-Type: application/pgp-signature
-----BEGIN PGP SIGNATURE-----
Version: 2.6.3in
iQCVAwUBNzHcdxaQN/7O/JIVAQHzfAP/bdkjKlaK2MhTmIPXxHwJzPZAUXFh5AyK
3ukjEDpv1ZgjOuTmYDHVmZlEhF0RPvOMcaqvBkePZUm/wMx5piqBu6WVdHoWtWwk
aoWOtcn+rBPqYM1MXZxfv+BcBnTah1mC2XizKIBGubyBJAyu9P6tFBd9yWZQsrIW
lGDXRCgSjn4=
=vy1m
-----END PGP SIGNATURE-----
--GPJrCs/72TxItFYR--
-
To unsubscribe from this list: send the line "unsubscribe linux-scsi" in
the body of a message to majordomo@vger.rutgers.edu
