Re: [PATCH 1/1 v3] drivers/nvme: default to 4k device page size

From: Christoph Hellwig
Date: Tue Nov 03 2015 - 08:18:34 EST


On Fri, Oct 30, 2015 at 02:35:11PM -0700, Nishanth Aravamudan wrote:
> diff --git a/drivers/block/nvme-core.c b/drivers/block/nvme-core.c
> index ccc0c1f93daa..a9a5285bdb39 100644
> --- a/drivers/block/nvme-core.c
> +++ b/drivers/block/nvme-core.c
> @@ -1717,7 +1717,12 @@ static int nvme_configure_admin_queue(struct nvme_dev *dev)
> u32 aqa;
> u64 cap = readq(&dev->bar->cap);
> struct nvme_queue *nvmeq;
> - unsigned page_shift = PAGE_SHIFT;
> + /*
> + * default to a 4K page size, with the intention to update this
> + * path in the future to accomodate architectures with differing
> + * kernel and IO page sizes.
> + */
> + unsigned page_shift = 12;
> unsigned dev_page_min = NVME_CAP_MPSMIN(cap) + 12;
> unsigned dev_page_max = NVME_CAP_MPSMAX(cap) + 12;

Looks good as a start. Note that all the MPSMIN/MAX checking could
be removed as NVMe devices must support 4k pages.
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