CentOS virt - Mar 2018 - kernel 4.9.86-30 missing mpt2sas module

Hi

I am attempting to setup Xen 4.10 with kernel 4.9.86-30 ( 
virt7-xen-410-testing, virt7-common-testing ) on CentOS7
After installing everything, the machine was unable to boot and hung in 
dracut stating it could not find its root device.

The testsystem I use is a somewhat aged Dell M915 Blade (Quad opteron 
61xx), using an MPT SAS controller for it's SAS boot drives. Stock 
CentOS 7 reports mpt2sas module being used to access the controller.
That module is not present in the modules directory of the 4.9.86:

4.9.86-30:
# pwd
/lib/modules/4.9.86-30.el7.x86_64
# find . -name "*mpt2*" -print
#

stock 3.10.0-693:
# pwd
/lib/modules/3.10.0-693.el7.x86_64
# find . -name "*mpt2*" -print
./kernel/drivers/scsi/mpt3sas/mpt2sas.ko.xz

The fun part is, that according to the shipped config, it should be there:
# grep MPT2 /boot/config-4.9.86-30.el7.x86_64
CONFIG_SCSI_MPT2SAS_MAX_SGE=128
CONFIG_SCSI_MPT2SAS=m

Any idea, what happened? I will try myself to build a new kernel from 
the corresponding source package to check, what went wrong.

As a side note: anyone here, who tried that combo? I know, it's somewhat 
cutting edge, but as I am finally looking into some sort of modern 
Xen4CentOS setup to replace our aged setup in our infrastructure, i 
thought i'd rather settle with something as new as possible to avoid 
running into "not supported anymore soon" issues. Check hypervisor 
support matrix on frontpage https://xenproject.org/

Regards
Thomas Weyergraf

On Tue, Mar 6, 2018 at 7:27 AM, T.Weyergraf <T.Weyergraf at virtfinity.de>
wrote:
> Hi
>
> I am attempting to setup Xen 4.10 with kernel 4.9.86-30 (
> virt7-xen-410-testing, virt7-common-testing ) on CentOS7
> After installing everything, the machine was unable to boot and hung in
> dracut stating it could not find its root device.
>
> The testsystem I use is a somewhat aged Dell M915 Blade (Quad opteron
61xx),
> using an MPT SAS controller for it's SAS boot drives. Stock CentOS 7
reports
> mpt2sas module being used to access the controller.
> That module is not present in the modules directory of the 4.9.86:
>
> 4.9.86-30:
> # pwd
> /lib/modules/4.9.86-30.el7.x86_64
> # find . -name "*mpt2*" -print
> #
>
> stock 3.10.0-693:
> # pwd
> /lib/modules/3.10.0-693.el7.x86_64
> # find . -name "*mpt2*" -print
> ./kernel/drivers/scsi/mpt3sas/mpt2sas.ko.xz
>
> The fun part is, that according to the shipped config, it should be there:
> # grep MPT2 /boot/config-4.9.86-30.el7.x86_64
> CONFIG_SCSI_MPT2SAS_MAX_SGE=128
> CONFIG_SCSI_MPT2SAS=m
>
> Any idea, what happened? I will try myself to build a new kernel from the
> corresponding source package to check, what went wrong.
In newer kernels (such as 4.9), the way the mpt2[3]sas driver is
provided has changed.

In the distro kernel config:

SCSI_MPT3SAS -> SAS 3.0 driver
SCSI_MPT2SAS -> SAS 2.0 driver

In the 4.x kernel config:

SCSI_MPT3SAS -> SAS 3.0 and SAS 2.0 device driver
SCSI_MPT2SAS -> Legacy MPT2SAS config option

config SCSI_MPT2SAS
        tristate "Legacy MPT2SAS config option"
        default n
        select SCSI_MPT3SAS
        depends on PCI && SCSI
        ---help---
        Dummy config option for backwards compatiblity: configure the MPT3SAS
        driver instead.

Therefore I suggest you try using the mpt3sas module. You can check to
see if your device is supported by the device ID paring (see lspci
-nn).

Akemi

On Tue, Mar 06, 2018 at 04:27:05PM +0100, T.Weyergraf
wrote:
> Hi
> 
> I am attempting to setup Xen 4.10 with kernel 4.9.86-30 (
> virt7-xen-410-testing, virt7-common-testing ) on CentOS7
> After installing everything, the machine was unable to boot and hung in
> dracut stating it could not find its root device.
> 
> The testsystem I use is a somewhat aged Dell M915 Blade (Quad opteron
61xx),
> using an MPT SAS controller for it's SAS boot drives. Stock CentOS 7
reports
> mpt2sas module being used to access the controller.
> That module is not present in the modules directory of the 4.9.86:
> 
> 4.9.86-30:
> # pwd
> /lib/modules/4.9.86-30.el7.x86_64
> # find . -name "*mpt2*" -print
> #
> 
> stock 3.10.0-693:
> # pwd
> /lib/modules/3.10.0-693.el7.x86_64
> # find . -name "*mpt2*" -print
> ./kernel/drivers/scsi/mpt3sas/mpt2sas.ko.xz
> 
> The fun part is, that according to the shipped config, it should be there:
> # grep MPT2 /boot/config-4.9.86-30.el7.x86_64
> CONFIG_SCSI_MPT2SAS_MAX_SGE=128
> CONFIG_SCSI_MPT2SAS=m
> 
> Any idea, what happened? I will try myself to build a new kernel from the
> corresponding source package to check, what went wrong.
>
Upstream Linux kernel migrated both the mpt2sas and mpt3sas drivers to a single
driver: mpt3sas, which should support all the devices.


-- Pasi
 
> As a side note: anyone here, who tried that combo? I know, it's
somewhat
> cutting edge, but as I am finally looking into some sort of modern
> Xen4CentOS setup to replace our aged setup in our infrastructure, i thought
> i'd rather settle with something as new as possible to avoid running
into
> "not supported anymore soon" issues. Check hypervisor support
matrix on
> frontpage https://xenproject.org/
> 
> Regards
> Thomas Weyergraf