From: Yanling Song <songyl@ramaxel.com>
To: Bart Van Assche <bvanassche@acm.org>
Cc: <martin.petersen@oracle.com>, <linux-scsi@vger.kernel.org>,
<songyl@ramaxel.com>
Subject: Re: [PATCH] spraid: initial commit of Ramaxel spraid driver
Date: Wed, 20 Oct 2021 00:33:23 +0000 [thread overview]
Message-ID: <20211020003323.61323f67@songyl> (raw)
In-Reply-To: <9d9d2f95-7782-85a7-b79a-ce481292c451@acm.org>
On Wed, 13 Oct 2021 15:00:07 -0700
Bart Van Assche <bvanassche@acm.org> wrote:
> On 10/12/21 11:50 PM, Yanling Song wrote:
> > On Tue, 12 Oct 2021 09:59:30 -0700
> > Bart Van Assche <bvanassche@acm.org> wrote:
> >> Why is it that SG_IO is not sufficient? This is something that
> >> should have been explained in the patch description.
> >
> > There are two cases that there are no SG devices and SG_IO cannot
> > work. 1. To access raid controller:
> > a. Raid controller is a scsi host, not a scsi device, so there
> > is no SG device associated with it.
> > b. Even there is a scsi device for raid controller, SG_IO
> > cannot work when something wrong with IO queue and only admin queue
> > can work;
> > 2. To access the physical disks behinds raid controller:
> > raid controller only reports VDs to OS and only VDs have SG
> > devices. OS has no idea about physical disks behinds raid
> > controller and there is no SG devices associated with physical
> > disks.
>
> Please take a look at the bsg_setup_queue() call in ufs_bsg_probe().
> That call associates a BSG queue with the UFS host. That queue
> supports requests of type struct ufs_bsg_request. The Fibre Channel
> transport driver does something similar. I believe that this is a
> better solution than introducing entirely new ioctls.
I wish there was a standard way to address the ioctrl issue.
Unfortunately ioctrl is the only way to meet our requirements as listed
in the above.
As discussed in previous megaraid's patchsets:
https://lore.kernel.org/linux-scsi/yq1inc2y019.fsf@oracle.com/, that's
why every raid controller has it's own ioctrl.
next prev parent reply other threads:[~2021-10-20 0:34 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-09-30 3:47 [PATCH] spraid: initial commit of Ramaxel spraid driver Yanling Song
2021-09-30 5:36 ` Randy Dunlap
2021-10-01 1:03 ` Yanling Song
2021-10-01 4:15 ` Christoph Hellwig
2021-10-08 9:22 ` Yanling Song
2021-10-09 3:58 ` Bart Van Assche
2021-10-09 13:32 ` Yanling Song
2021-10-10 3:52 ` Bart Van Assche
2021-10-11 8:34 ` Yanling Song
2021-10-11 19:40 ` Bart Van Assche
2021-10-12 11:10 ` Yanling Song
2021-10-11 19:54 ` Bart Van Assche
2021-10-12 14:49 ` Yanling Song
2021-10-12 16:59 ` Bart Van Assche
2021-10-13 6:50 ` Yanling Song
2021-10-13 22:00 ` Bart Van Assche
2021-10-15 5:48 ` Yanling Song
2021-10-20 0:33 ` Yanling Song [this message]
2021-10-20 3:24 ` Bart Van Assche
2021-11-03 1:43 ` Yanling Song
2021-11-05 13:02 ` Yanling Song
2021-11-05 16:13 ` Bart Van Assche
2021-11-06 8:30 ` Yanling Song
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