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

[Heiner Kallweit]

On 18.01.2019 09:48, Krzysztof Kozlowski wrote:
> On Fri, 18 Jan 2019 at 09:39, Krzysztof Kozlowski <krzk@xxxxxxxxxx> wrote:
>>
>> Hi,
>>
>> 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.

> Best regards,
> Krzysztof
> 
Heiner