Re: [PATCH v6 01/11] mtd: core: always create master device

[Guenter Roeck]

On 6/9/25 08:16, Usyskin, Alexander wrote:
> > Subject: Re: [PATCH v6 01/11] mtd: core: always create master device
> >
> > On 6/9/25 05:23, Usyskin, Alexander wrote:
> > > > Subject: Re: [PATCH v6 01/11] mtd: core: always create master device
> > > >
> > > >
> > > > > > > > Several of my qemu boot tests fail to boot from mtd devices with this
> > > > patch
> > > > > > > > in the mainline kernel. Reverting it fixes the problem. As far as I can
> > > > > > > > see this affects configurations with
> > > > CONFIG_MTD_PARTITIONED_MASTER=y
> > > > > > > > when
> > > > > > > > trying to boot from an mtd partition other than mtdblock0, with the
> > > > > > > > mtd partition data in devicetree (.../aspeed/openbmc-flash-
> > layout.dtsi).
> > > > > > > > Is there a guidance describing the changed behavior, by any chance,
> > > > > > > > and how the boot command line now needs to look like when using
> > one
> > > > of
> > > > > > > > the flash partitions as root file system ?
> > > > > > > >
> > > > > > > > Thanks,
> > > > > > > > Guenter
> > > > > > >
> > > > > > > I've tried to make is as transparent as possible for the existing users.
> > > > > > > Only change is that now every partition has master that is not
> > partitioned.
> > > > > > > Is the CONFIG_MTD_PARTITIONED_MASTER=n fixed the problem for
> > you?
> > > > > > No change is expected, can you please describe the devices that you
> > > > > > observe with and without the patch? Maybe there is something wrong in
> > > > > > the core logic.
> > > > >
> > > > > I am trying to boot supermicro-x11spi-bmc in qemu from flash partition 6.
> > > > > The qemu command line is something like
> > > > >
> > > > >       qemu-system-arm -M supermicro-x11spi-bmc,fmc-
> > > > model=n25q256a13,spi-model=n25q256a13 \
> > > > > 	-kernel arch/arm/boot/zImage -no-reboot -snapshot \
> > > > > 	-audio none \
> > > > > 	-drive file=/tmp/flash,format=raw,if=mtd,index=1 \
> > > > > 	-nic user \
> > > > > 	--append "root=/dev/mtdblock6 rootwait console=ttyS4,115200
> > > > earlycon=uart8250,mmio32,0x1e784000,115200n8" \
> > > > > 	-dtb arch/arm/boot/dts/aspeed/aspeed-bmc-supermicro-x11spi.dtb
> > > > \
> > > > > 	-nographic -monitor null -serial stdio
> > > > >
> > > > > This is with aspeed_g5_defconfig. Note that the flash models need to be
> > > > specified.
> > > > > The default flashes are no longer recognized when booting from qemu
> > since
> > > > commit
> > > > > 947c86e481a0 ("mtd: spi-nor: macronix: Drop the redundant flash info
> > > > fields").
> > > > > The above only works with this patch reverted (or with v6.15 and older, of
> > > > course).
> > > > > Guenter
> > > >
> > > > Alexander, can you please investigate? We need a fix because Guenter
> > > > might not be the only affecter user. Otherwise this patch can't stand,
> > > > unfortunately.
> > > >
> > > > Thanks,
> > > > Miquèl
> > >
> > > Maybe something is moved, and it is not /dev/mtdblock6 now.
> >
> > With this patch:
> >
> > # ls -l /dev/*mtd*
> > crw-------    1 root     root       90,   0 Jan  1 00:00 /dev/mtd0
> > crw-------    1 root     root       90,   1 Jan  1 00:00 /dev/mtd0ro
> > crw-------    1 root     root       90,   2 Jan  1 00:00 /dev/mtd1
> > crw-------    1 root     root       90,   3 Jan  1 00:00 /dev/mtd1ro
> > crw-------    1 root     root      244,   0 Jan  1 00:00 /dev/mtd_master0
> > crw-------    1 root     root      244,   1 Jan  1 00:00 /dev/mtd_master1
> > brw-------    1 root     root       31,   0 Jan  1 00:00 /dev/mtdblock0
> > brw-------    1 root     root       31,   1 Jan  1 00:00 /dev/mtdblock1
> > ~ # ls /proc/mtd
> > /proc/mtd
> > ~ # cat /proc/mtd
> > dev:    size   erasesize  name
> > mtd0: 02000000 00010000 "bmc"
> > mtd1: 02000000 00010000 "pnor"
> >
> > After reverting it:
> >
> > # ls -l /dev/mtd*
> > crw-------    1 root     root       90,   0 Jan  1 00:00 /dev/mtd0
> > crw-------    1 root     root       90,   1 Jan  1 00:00 /dev/mtd0ro
> > crw-------    1 root     root       90,   2 Jan  1 00:00 /dev/mtd1
> > crw-------    1 root     root       90,   3 Jan  1 00:00 /dev/mtd1ro
> > crw-------    1 root     root       90,   4 Jan  1 00:00 /dev/mtd2
> > crw-------    1 root     root       90,   5 Jan  1 00:00 /dev/mtd2ro
> > crw-------    1 root     root       90,   6 Jan  1 00:00 /dev/mtd3
> > crw-------    1 root     root       90,   7 Jan  1 00:00 /dev/mtd3ro
> > crw-------    1 root     root       90,   8 Jan  1 00:00 /dev/mtd4
> > crw-------    1 root     root       90,   9 Jan  1 00:00 /dev/mtd4ro
> > crw-------    1 root     root       90,  10 Jan  1 00:00 /dev/mtd5
> > crw-------    1 root     root       90,  11 Jan  1 00:00 /dev/mtd5ro
> > crw-------    1 root     root       90,  12 Jan  1 00:00 /dev/mtd6
> > crw-------    1 root     root       90,  13 Jan  1 00:00 /dev/mtd6ro
> > brw-------    1 root     root       31,   0 Jan  1 00:00 /dev/mtdblock0
> > brw-------    1 root     root       31,   1 Jan  1 00:00 /dev/mtdblock1
> > brw-------    1 root     root       31,   2 Jan  1 00:00 /dev/mtdblock2
> > brw-------    1 root     root       31,   3 Jan  1 00:00 /dev/mtdblock3
> > brw-------    1 root     root       31,   4 Jan  1 00:00 /dev/mtdblock4
> > brw-------    1 root     root       31,   5 Jan  1 00:00 /dev/mtdblock5
> > brw-------    1 root     root       31,   6 Jan  1 00:00 /dev/mtdblock6
> > ~ # cat /proc/mtd
> > dev:    size   erasesize  name
> > mtd0: 02000000 00010000 "bmc"
> > mtd1: 00060000 00010000 "u-boot"
> > mtd2: 00020000 00010000 "u-boot-env"
> > mtd3: 00440000 00010000 "kernel"
> > mtd4: 01740000 00010000 "rofs"
> > mtd5: 00400000 00010000 "rwfs"
> > mtd6: 02000000 00010000 "pnor"
> >
> > I am trying to boot from "pnor". It looks like the partition data (from
> > devicetree)
> > is now ignored. mtdblock6 used to be the second flash.
> >
> > Guenter
>
> Is this with CONFIG_MTD_PARTITIONED_MASTER?

Yes

> I think that mtd_is_partition is ambiguous now.
> We always have master partition when CONFIG_MTD_PARTITIONED_MASTER
> is enabled and parent check is useless.
> We must check grandparent in this case.
> Miquel, am I right?
>
> We can return to older patch version that have created partition
> instead of the master device.
> Or try to fix mtd_is_partition, like below.
> Guenter, is below patch helps?
No, it does not make a difference. Partitions are still not created.

Guenter