Checking module parameters

Checking module parameters

[David Wagner]

Is there a way to tell what options have been applied to a currently
loaded kernel module?

I'm trying to force libata to use 1.5Gbps rather than 3Gbps, so I created
a file /etc/modprobe.d/local containing:
  options libata force=1.5Gbps
However my SATA drive gets loaded at 3Gbps.  I'm trying to figure out how
to debug this so that I can tell whether the option got correctly applied
to the libata module, and if not, how to force the SATA link to 1.5Gbps.
Any suggestions or ideas?

(I can't set libata.force=1.5Gbps as a kernel argument because on my
Fedora kernel, libata is loaded as a module rather than built into the
kernel.  I can't run "modprobe libata force=1.5Gbps" by hand because
I've got SATA drives, so the libata module is automatically loaded before
I get shell access.)

Re: Checking module parameters

[Alexey Dobriyan]

On Sun, Jan 18, 2009 at 1:26 AM, David Wagner <daw@cs.berkeley.edu> wrote:
> Is there a way to tell what options have been applied to a currently
> loaded kernel module?

/sys/module/[module name]/parameters/ (if i remember correctly)

> I'm trying to force libata to use 1.5Gbps rather than 3Gbps, so I created
> a file /etc/modprobe.d/local containing:
>  options libata force=1.5Gbps
> However my SATA drive gets loaded at 3Gbps.  I'm trying to figure out how
> to debug this so that I can tell whether the option got correctly applied
> to the libata module, and if not, how to force the SATA link to 1.5Gbps.
> Any suggestions or ideas?
>
> (I can't set libata.force=1.5Gbps as a kernel argument because on my
> Fedora kernel, libata is loaded as a module rather than built into the
> kernel.  I can't run "modprobe libata force=1.5Gbps" by hand because
> I've got SATA drives, so the libata module is automatically loaded before
> I get shell access.)

This may not work if libata module is loaded from initrd.

Re: Checking module parameters

[Robert Hancock]

David Wagner wrote:
> Is there a way to tell what options have been applied to a currently
> loaded kernel module?
> 
> I'm trying to force libata to use 1.5Gbps rather than 3Gbps, so I created
> a file /etc/modprobe.d/local containing:
>   options libata force=1.5Gbps
> However my SATA drive gets loaded at 3Gbps.  I'm trying to figure out how
> to debug this so that I can tell whether the option got correctly applied
> to the libata module, and if not, how to force the SATA link to 1.5Gbps.
> Any suggestions or ideas?
> 
> (I can't set libata.force=1.5Gbps as a kernel argument because on my
> Fedora kernel, libata is loaded as a module rather than built into the
> kernel.  I can't run "modprobe libata force=1.5Gbps" by hand because
> I've got SATA drives, so the libata module is automatically loaded before
> I get shell access.)

Rebuilding the initrd with that option set should cause the initrd to 
pass the option into the libata module when the initrd script loads it. 
Unfortunately the current Fedora mkinitrd is broken such that this 
doesn't work. I'm rather disappointed by the lack of response to this 
bug as it seems like it should be easily resolved and causes serious 
problems with debugging certain issues, as you've found. Anyone know who 
needs to be hit with a clue-by-four to get this fixed?

https://bugzilla.redhat.com/show_bug.cgi?id=457870

Re: Checking module parameters

[Yanko Kaneti]

David Wagner <daw <at> cs.berkeley.edu> writes:

> (I can't set libata.force=1.5Gbps as a kernel argument because on my
> Fedora kernel, libata is loaded as a module rather than built into the
> kernel.  

That used to be true until module-init-tools-3.5 , i.e.  you can in Fedora 10
and rawhide.

Cheers

Re: Checking module parameters

[Alan Cox]

> (I can't set libata.force=1.5Gbps as a kernel argument because on my
> Fedora kernel, libata is loaded as a module rather than built into the
> kernel.  I can't run "modprobe libata force=1.5Gbps" by hand because
> I've got SATA drives, so the libata module is automatically loaded before
> I get shell access.)

Best to ask on the Fedora lists for fedora specific config help. If I
remember rightly you need to update the module options in the initrd...

Alan

Re: Checking module parameters

[Nick Craig-Wood]

David Wagner <daw@cs.berkeley.edu> wrote:
>  Is there a way to tell what options have been applied to a currently
>  loaded kernel module?
> 
>  I'm trying to force libata to use 1.5Gbps rather than 3Gbps, so I created
>  a file /etc/modprobe.d/local containing:
>    options libata force=1.5Gbps
>  However my SATA drive gets loaded at 3Gbps.  I'm trying to figure out how
>  to debug this so that I can tell whether the option got correctly applied
>  to the libata module, and if not, how to force the SATA link to 1.5Gbps.
>  Any suggestions or ideas?
> 
>  (I can't set libata.force=1.5Gbps as a kernel argument because on my
>  Fedora kernel, libata is loaded as a module rather than built into the
>  kernel.  I can't run "modprobe libata force=1.5Gbps" by hand because
>  I've got SATA drives, so the libata module is automatically loaded before
>  I get shell access.)

I had to do this recently (under debian I ended up putting
"libata force=1.5Gbps" into /etc/modules)

You can check it is working by looking for something like this in the log

[    2.345058] ata1: FORCE: PHY spd limit set to 1.5Gbps
[    2.345058] ata1: SATA max UDMA/133 abar m2048@0xfb106000 port 0xfb106100 irq 218
[    2.345058] ata2: FORCE: PHY spd limit set to 1.5Gbps
[    2.345058] ata2: SATA max UDMA/133 abar m2048@0xfb106000 port 0xfb106180 irq 218
[    2.345058] ata3: FORCE: PHY spd limit set to 1.5Gbps
[    2.345058] ata3: SATA max UDMA/133 abar m2048@0xfb106000 port 0xfb106200 irq 218
[    2.345058] ata4: FORCE: PHY spd limit set to 1.5Gbps
[    2.345058] ata4: SATA max UDMA/133 abar m2048@0xfb106000 port 0xfb106280 irq 218
[    2.345058] ata5: FORCE: PHY spd limit set to 1.5Gbps
[    2.345058] ata5: SATA max UDMA/133 abar m2048@0xfb106000 port 0xfb106300 irq 218
[    2.345058] ata6: FORCE: PHY spd limit set to 1.5Gbps
[    2.345058] ata6: SATA max UDMA/133 abar m2048@0xfb106000 port 0xfb106380 irq 218

-- 
Nick Craig-Wood <nick@craig-wood.com> -- http://www.craig-wood.com/nick

Re: Checking module parameters

[Stefan Richter]

Nick Craig-Wood wrote:
> David Wagner <daw@cs.berkeley.edu> wrote:
>>  Is there a way to tell what options have been applied to a currently
>>  loaded kernel module?
>> 
>>  I'm trying to force libata to use 1.5Gbps rather than 3Gbps,
...
> I had to do this recently (under debian I ended up putting
> "libata force=1.5Gbps" into /etc/modules)
> 
> You can check it is working by looking for something like this in the log
> 
> [    2.345058] ata1: FORCE: PHY spd limit set to 1.5Gbps
> [    2.345058] ata1: SATA max UDMA/133 abar m2048@0xfb106000 port 0xfb106100 irq 218

There is also /sys/module/*/parameters/* which can be read and in some
cases even be written.
-- 
Stefan Richter
-=====-==--= ---= =--==
http://arcgraph.de/sr/

Re: Checking module parameters

[Nick Craig-Wood]

On Mon, Jan 19, 2009 at 11:19:34AM +0100, Stefan Richter wrote:
> Nick Craig-Wood wrote:
> > David Wagner <daw@cs.berkeley.edu> wrote:
> >>  Is there a way to tell what options have been applied to a currently
> >>  loaded kernel module?
> >> 
> >>  I'm trying to force libata to use 1.5Gbps rather than 3Gbps,
> ...
> > I had to do this recently (under debian I ended up putting
> > "libata force=1.5Gbps" into /etc/modules)
> > 
> > You can check it is working by looking for something like this in the log
> > 
> > [    2.345058] ata1: FORCE: PHY spd limit set to 1.5Gbps
> > [    2.345058] ata1: SATA max UDMA/133 abar m2048@0xfb106000 port 0xfb106100 irq 218
> 
> There is also /sys/module/*/parameters/* which can be read and in some
> cases even be written.

It doesn't appear to show the force parameter.  From the same server
as above :-

$ more /sys/module/libata/parameters/* | cat
::::::::::::::
/sys/module/libata/parameters/acpi_gtf_filter
::::::::::::::
3
::::::::::::::
/sys/module/libata/parameters/allow_tpm
::::::::::::::
0
::::::::::::::
/sys/module/libata/parameters/ata_probe_timeout
::::::::::::::
7500
::::::::::::::
/sys/module/libata/parameters/atapi_dmadir
::::::::::::::
0
::::::::::::::
/sys/module/libata/parameters/atapi_enabled
::::::::::::::
1
::::::::::::::
/sys/module/libata/parameters/atapi_passthru16
::::::::::::::
1
::::::::::::::
/sys/module/libata/parameters/dma
::::::::::::::
7
::::::::::::::
/sys/module/libata/parameters/fua
::::::::::::::
0
::::::::::::::
/sys/module/libata/parameters/ignore_hpa
::::::::::::::
0
::::::::::::::
/sys/module/libata/parameters/noacpi
::::::::::::::
0

-- 
Nick Craig-Wood <nick@craig-wood.com> -- http://www.craig-wood.com/nick

Re: Checking module parameters

[Stefan Richter]

Nick Craig-Wood wrote:
> On Mon, Jan 19, 2009 at 11:19:34AM +0100, Stefan Richter wrote:
>> There is also /sys/module/*/parameters/* which can be read and in some
>> cases even be written.
> 
> It doesn't appear to show the force parameter.

You are right.
>From drivers/ata/libata-core.c:

|> static char ata_force_param_buf[PAGE_SIZE] __initdata;
|> /* param_buf is thrown away after initialization, disallow read */
|> module_param_string(force, ata_force_param_buf,
sizeof(ata_force_param_buf), 0);
|> MODULE_PARM_DESC(force, "Force ATA configurations including cable
type, link speed and transfer mode (see
Documentation/kernel-parameters.txt for details)");

The 0 in module_param_string are the sysfs file permissions of libata.force.

And __initdata means that the memory goes away after ata_init() returned.
-- 
Stefan Richter
-=====-==--= ---= =--==
http://arcgraph.de/sr/