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Date: Mon, 16 Jun 2025 13:35:05 +0200
From: Christoph Hellwig <hch@lst.de>
To: Daniel Gomez <da.gomez@kernel.org>
Cc: Christoph Hellwig <hch@lst.de>, Jens Axboe <axboe@kernel.dk>,
	Keith Busch <kbusch@kernel.org>, Sagi Grimberg <sagi@grimberg.me>,
	Chaitanya Kulkarni <kch@nvidia.com>,
	Kanchan Joshi <joshi.k@samsung.com>,
	Leon Romanovsky <leon@kernel.org>,
	Nitesh Shetty <nj.shetty@samsung.com>,
	Logan Gunthorpe <logang@deltatee.com>, linux-block@vger.kernel.org,
	linux-nvme@lists.infradead.org
Subject: Re: [PATCH 7/9] nvme-pci: convert the data mapping blk_rq_dma_map
Message-ID: <20250616113505.GA22121@lst.de>
References: <20250610050713.2046316-1-hch@lst.de> <20250610050713.2046316-8-hch@lst.de> <871b014b-e308-4f20-9701-5581beee91ed@kernel.org>
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On Mon, Jun 16, 2025 at 09:49:47AM +0200, Daniel Gomez wrote:
> >  #define NVME_MAX_SEGS \
> > -	min(NVME_CTRL_PAGE_SIZE / sizeof(struct nvme_sgl_desc), \
> > -	    (PAGE_SIZE / sizeof(struct scatterlist)))
> > +	(NVME_CTRL_PAGE_SIZE / sizeof(struct nvme_sgl_desc))
> 
> IIRC, I've seen in the commit history going from PAGE_SIZE to CC.MPS for
> different cases in the driver. PRPs requires contiguous regions to be CC.MPS,
> i.e use NVME_CTRL_PAGE_SIZE for PRP lists and entries. But I think that is not a
> limit for SGLs. Can we use PAGE_SIZE here?

Sure.  Separate unrelated patch, though.