Re: [BUG bisect] Missing Micrel driver on VF50 (net: phy: check return code when requesting PHY driver module)

On Tue, 22 Jan 2019 at 14:52, Geert Uytterhoeven [off-list ref] wrote:

Hi Heiner,

On Fri, Jan 18, 2019 at 9:58 PM Heiner Kallweit [off-list ref] wrote:

quoted

On 18.01.2019 09:48, Krzysztof Kozlowski wrote:

quoted

On Fri, 18 Jan 2019 at 09:39, Krzysztof Kozlowski [off-list ref] wrote:

quoted

On today's next (next-20190118) my Colibri VF50 board fails to boot up
from network (DHCP, NFSv4 root). Looks like missing network adapter.
Expected:
[ 3.041773] Micrel KSZ8041 400d1000.ethernet-1:00: attached PHY driver
[Micrel KSZ8041] (mii_bus:phy_addr=400d1000.ethernet-1:00, irq=POLL)

Result:
[ 15.614964] Root-NFS: no NFS server address
[ 15.619353] VFS: Unable to mount root fs via NFS, trying floppy.
[ 15.626762] VFS: Cannot open root device "nfs" or unknown-block(2,0): error -6
[ 15.634252] Please append a correct "root=" boot option; here are the
available partitions:
[ 15.642791] 0100 16384 ram0
[ 15.642804] (driver?)
[ 15.649076] Kernel panic - not syncing: VFS: Unable to mount root fs
on unknown-block(2,0)
[ 15.657423] ---[ end Kernel panic - not syncing: VFS: Unable to mount
root fs on unknown-block(2,0) ]---

Bisect pointed to:
    net: phy: check return code when requesting PHY driver module

I see now in the logs:
[ 2.436822] mdio_bus 400d1000.ethernet-1:00: error -2 loading PHY
driver module for ID 0x00221513
which is kind of misleading. There is no initramfs so there is no
usermod library at this point. It is not needed. This seems to break
all DHCP/NFS root boots without initrd/initramfs.

Thanks for the report. Could you please provide your kernel config
and the syslog of a boot before or w/o the patch in question?

If you boot via nfs then I'd expect that the PHY driver is built-in and
not a module. Therefore it's not fully clear to me yet why
request_module() returns -ENOENT.

I'm seeing the same booting nfsroot on several Renesas boards.
E.g. on r8a7791/koelsch:

    mdio_bus ee700000.ethernet-ffffffff:01: error -2 loading PHY
driver module for ID 0x00221537
    sh-eth ee700000.ethernet: MDIO init failed: -2

Hi Geert,

There is a follow up patch:
https://www.spinics.net/lists/netdev/msg545573.html

Best regards,
Krzysztof