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Date: Tue, 2 Jun 2015 19:11:28 +0000 (UTC)
From: Keith Busch <keith.busch@intel.com>
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Subject: Re: [Qemu-devel] [edk2] NVMe question
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To: Laszlo Ersek <lersek@redhat.com>
Cc: Keith Busch <keith.busch@intel.com>, "Anbazhagan,
	Baraneedharan" <anbazhagan@hp.com>, edk2-devel@lists.sourceforge.net, Feng Tian <feng.tian@intel.com>, qemu devel list <qemu-devel@nongnu.org>

Hi,

On Tue, 2 Jun 2015, Laszlo Ersek wrote:
> removed the nonzero initialization of Cc.Iosqes (submission queue size?)
> and Cc.Iocqes (completion queue size?) in function
> NvmeEnableController(). And the removal of these field initializations
> seems to cause the early sanity check in QEMU's nvme_start_ctrl() to
> fail -- my guess at least.
>
> The question is now if QEMU is right (according to the NVMe spec) to
> require those fields, or if edk2 is right not to initialize them.

The host driver definitely needs to initialize these for the device to
understand the queue's entry sizes. Without proper values, it would have
no idea how much memory a queue occupies. If you have a real device that
ignores these, it's breaking spec.