From: John Garry <john.g.garry@oracle.com>
To: Christoph Hellwig <hch@lst.de>
Cc: "Ionut Nechita (Wind River)" <ionut.nechita@windriver.com>,
m.szyprowski@samsung.com, kbusch@kernel.org, axboe@kernel.dk,
sagi@grimberg.me, robin.murphy@arm.com,
martin.petersen@oracle.com, damien.lemoal@opensource.wdc.com,
ahuang12@lenovo.com, iommu@lists.linux.dev,
linux-nvme@lists.infradead.org, linux-kernel@vger.kernel.org,
stable@vger.kernel.org, ionut_n2001@yahoo.com,
sunlightlinux@gmail.com
Subject: Re: [PATCH v1 0/2] dma: fix dma_opt_mapping_size() returning bogus value when no backend hint exists
Date: Tue, 17 Mar 2026 15:18:54 +0000 [thread overview]
Message-ID: <8b27a545-7d3c-44b1-a9e6-16968fa2e2a4@oracle.com> (raw)
In-Reply-To: <20260317143651.GA5186@lst.de>
On 17/03/2026 14:36, Christoph Hellwig wrote:
> On Tue, Mar 17, 2026 at 09:11:59AM +0000, John Garry wrote:
>> For SAS controllers, don't we limit shost->opt_sectors at
>> shost->max_sectors, and then in sd_revalidate_disk() this value is ignored
>> as sdkp->opt_xfer_blocks would be smaller, right?
> That assumes opt_xfer_blocks is actually set. It's an optional and
> relatively recent SCSI feature. So don't expect crappy SSDs or
> RAID controllers faking up SCSI in shitty firmware to actually set
> it.
Sure, and then we would have io_opt at max_sectors, and it seems that
value is totally configurable for that HBA driver.
However I still find the values reported strange:
swidth=4095 / sunit=2
I thought that they were from io_opt and io_min, and
blk_validate_limits() does rounding to PBS, except io_min has no
rounding for > PBS.
prev parent reply other threads:[~2026-03-17 15:19 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-03-16 20:39 Ionut Nechita (Wind River)
2026-03-16 20:39 ` [PATCH v1 1/2] dma: return 0 from dma_opt_mapping_size() when no real " Ionut Nechita (Wind River)
2026-03-17 9:43 ` Robin Murphy
2026-03-17 14:19 ` Christoph Hellwig
2026-03-16 20:39 ` [PATCH v1 2/2] nvme-pci: handle dma_opt_mapping_size() returning 0 Ionut Nechita (Wind River)
2026-03-16 21:21 ` Damien Le Moal
2026-03-17 8:55 ` John Garry
2026-03-17 14:14 ` Christoph Hellwig
2026-03-17 9:11 ` [PATCH v1 0/2] dma: fix dma_opt_mapping_size() returning bogus value when no backend hint exists John Garry
2026-03-17 9:18 ` Damien Le Moal
2026-03-17 14:36 ` Christoph Hellwig
2026-03-17 15:18 ` John Garry [this message]
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