Re: [RFC 01/22] part: call part_init() in blk_get_device_by_str() only for MMC

Simon Glass
2021-10-11T14:33:14Z

Hi Heinrich,

On Mon, 11 Oct 2021 at 04:07, Heinrich Schuchardt <xypron.glpk@gmx.de> wrote:
>
>
>
> On 10/1/21 13:48, Peter Robinson wrote:
> > On Fri, Oct 1, 2021 at 6:03 AM AKASHI Takahiro
> > <takahiro.akashi@linaro.org> wrote:
> >>
> >> In blk_get_device_by_str(), the comment says: "Updates the partition table
> >> for the specified hw partition."
> >> Since hw partition is supported only on MMC, it makes no sense to do so
> >> for other devices.
> >
> > Is it not also supported on UFS, and I believe it may also be an
> > option in the NVME spec too.
>
> An NVMe device may expose multiple namespaces. blk_create_devicef() is
> called for each namespace.
>
> A SCSI device may have multiple LUNs. blk_create_devicef() is called for
> each LUN.
>
> This is what the tree shown by 'dm tree' with on NVMe namespace and one LUN.
>
> Class Index Driver Name
> ---------------------------------------------------------------------
> root 0 root_driver root_driver
> simple_bus 0 simple_bus |- soc
> spi 1 sifive_spi | |- spi@10050000
> mmc 0 mmc_spi | | `- mmc@0
> blk 0 mmc_blk | | `- mmc@0.blk
> pci 0 pcie_sifive | |- pcie@e00000000
> pci 1 pci_bridge_drv | | `- pci_0:0.0
> pci 2 pci_bridge_drv | | `- pci_1:0.0
> pci 5 pci_bridge_drv | | |- pci_2:3.0
> ahci 0 ahci_pci | | | `- ahci_pci
> scsi 0 ahci_scsi | | | `- ahci_scsi
> blk 2 scsi_blk | | | `- ahci_scsi.id0lun0
> pci 6 pci_bridge_drv | | |- pci_2:4.0
> nvme 0 nvme | | | `- nvme#0
> blk 1 nvme-blk | | | `- nvme#0.blk#1
>
> Namespaces and LUNs are modeled as block devices (class = 'blk').

So multiple block devices per NVMe device? I did not know that was supported.

We need a sandbox driver for NVMe as it has no tests at present. Since
it has no tests, I don't think we can expect people to know how to
maintain whatever functionality is there.

[..]

Regards,
Simon