Date: Sat, 23 Mar 2019 14:35:36 -0700 From: Chuck Tuffli <chuck@freebsd.org> To: freebsd-virtualization@freebsd.org Subject: Re: emulated PCI device BAR size Message-ID: <CAKAYmML9jAc4WfJ8NP9iiFWY4R7DgU9SKyF_ZiNxt5FvSXQfhA@mail.gmail.com> In-Reply-To: <CAKAYmMKd5o=f8Z5uzF6pQnZqWLzRLAL3U7iM5inuodQs92pudA@mail.gmail.com> References: <CAKAYmMKd5o=f8Z5uzF6pQnZqWLzRLAL3U7iM5inuodQs92pudA@mail.gmail.com>
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On Mon, Mar 18, 2019 at 10:15 AM Chuck Tuffli <chuck@freebsd.org> wrote: > > In debugging why Windows doesn't like bhyve's NVMe device emulation, > another developer mentioned that the NVMe specification defines the > minimum size of BAR[0] to be 16K bytes. And while most OS don't > enforce this requirement, evidently, Windows does. > > On the surface, a "minimum BAR size" sounds odd, but the MMIO BAR in > NVMe includes the doorbell registers for each queue. And since the > maximum number of queues is implementation specific, there isn't a > fixed size for the BAR. > > So my question is how to best fix this. The easiest would be to add a > check to the BAR size calculation in pci_nvme.c along the lines of: > #define NVME_MMIO_SPACE_MIN (1 << 14) > ... > pci_membar_sz = MAX( <calculation based on queue count>, > NVME_MMIO_SPACE_MIN); I went down this route and have a patch up for review (https://reviews.freebsd.org/D19676) if anyone is interested. --chuck
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