MIPS 4KEc with 2.6.15

MIPS 4KEc with 2.6.15

[Jorgen Lundman]

Hello list,

I have an embedded device running 2.6.15 kernel on a MIPS 4KEc 300MHz 
CPU. It was configured for Sigma's tango2 board, which I know nothing 
about, so I picked a mips-board by random, "atlas", and found I can 
produce working kernel module compiles.

However, when I compiled FUSE kernel module, it behaves erratically in a 
way making the FUSE developer think I may have come across the cache 
coherency bug in arm and mips, fixed sometime around 2.6.17.

Since I can not change the kernel that is running, I was looking for 
alternate solutions. FUSE itself has a work around, that calls 
flush_cache_page(), but I found that mips-board atlas does not have this 
defined:

fuse: Unknown symbol flush_cache_page

Should I try other mips-boards that may have this function call defined? 
Do I have other ways to avoid the cache coherence bug?

The /proc/ksyms is gone, so I do not think I am able to check what 
symbols their kernel has.

Lund


-- 
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Re: MIPS 4KEc with 2.6.15

[Ralf Baechle]

On Mon, Jan 07, 2008 at 09:39:29AM +0900, Jorgen Lundman wrote:

> I have an embedded device running 2.6.15 kernel on a MIPS 4KEc 300MHz CPU. 
> It was configured for Sigma's tango2 board, which I know nothing about, so 
> I picked a mips-board by random, "atlas", and found I can produce working 
> kernel module compiles.
>
> However, when I compiled FUSE kernel module, it behaves erratically in a 
> way making the FUSE developer think I may have come across the cache 
> coherency bug in arm and mips, fixed sometime around 2.6.17.
>
> Since I can not change the kernel that is running, I was looking for 
> alternate solutions. FUSE itself has a work around, that calls 
> flush_cache_page(), but I found that mips-board atlas does not have this 
> defined:

While you may not be able to change the kernel running on your board,
you should be building any modules against kernel headers of the exact
kernel running and configured for the platform and CPU you're using.

Mixing and matching different versions and configurations may work but
frequently it will fail silently.

  Ralf

Re: MIPS 4KEc with 2.6.15

[Jorgen Lundman]

Sorry, I should have said, I grabbed 2.6.15.7 to use. And after the 
issues, I even tried the exact 2.6.15 tarball off Sigmas FTP with the 
same results. It does not define flush_cache_pages for Atlas board, only 
SGI IPxx from what I can tell.

Ralf Baechle wrote:
> On Mon, Jan 07, 2008 at 09:39:29AM +0900, Jorgen Lundman wrote:
> 
>> I have an embedded device running 2.6.15 kernel on a MIPS 4KEc 300MHz CPU. 
>> It was configured for Sigma's tango2 board, which I know nothing about, so 
>> I picked a mips-board by random, "atlas", and found I can produce working 
>> kernel module compiles.
>>
>> However, when I compiled FUSE kernel module, it behaves erratically in a 
>> way making the FUSE developer think I may have come across the cache 
>> coherency bug in arm and mips, fixed sometime around 2.6.17.
>>
>> Since I can not change the kernel that is running, I was looking for 
>> alternate solutions. FUSE itself has a work around, that calls 
>> flush_cache_page(), but I found that mips-board atlas does not have this 
>> defined:
> 
> While you may not be able to change the kernel running on your board,
> you should be building any modules against kernel headers of the exact
> kernel running and configured for the platform and CPU you're using.
> 
> Mixing and matching different versions and configurations may work but
> frequently it will fail silently.
> 
>   Ralf
> 

-- 
Jorgen Lundman       | <lundman@lundman.net>
Unix Administrator   | +81 (0)3 -5456-2687 ext 1017 (work)
Shibuya-ku, Tokyo    | +81 (0)90-5578-8500          (cell)
Japan                | +81 (0)3 -3375-1767          (home)

Re: MIPS 4KEc with 2.6.15

[David Daney]

Jorgen Lundman wrote:
>
> Hello list,
>
> I have an embedded device running 2.6.15 kernel on a MIPS 4KEc 300MHz
> CPU. It was configured for Sigma's tango2 board, which I know nothing
> about, so I picked a mips-board by random, "atlas", and found I can
> produce working kernel module compiles.
>
> However, when I compiled FUSE kernel module, it behaves erratically in
> a way making the FUSE developer think I may have come across the cache
> coherency bug in arm and mips, fixed sometime around 2.6.17.
>
> Since I can not change the kernel that is running, I was looking for
> alternate solutions. FUSE itself has a work around, that calls
> flush_cache_page(), but I found that mips-board atlas does not have
> this defined:
>
> fuse: Unknown symbol flush_cache_page

There are cache coherency issues on the 8634.  You should be using the
vendor's very most recent kernels.  For me they seem to have resolved
the cache issues.

Also as noted by others, you need the exact kernel sources if you are
going to build working modules.

David Daney

Re: MIPS 4KEc with 2.6.15

[Mark Lin]

Jorgen,

You should not be using the atlas definition.  Try the tangox one instead.

With the flush_cache_page changes, FUSE works fine for me using 2.6.15
and Sigma's tango2 board.

Mark Lin

On Jan 7, 2008 10:52 AM, David Daney <ddaney@avtrex.com> wrote:
> Jorgen Lundman wrote:
> >
> > Hello list,
> >
> > I have an embedded device running 2.6.15 kernel on a MIPS 4KEc 300MHz
> > CPU. It was configured for Sigma's tango2 board, which I know nothing
> > about, so I picked a mips-board by random, "atlas", and found I can
> > produce working kernel module compiles.
> >
> > However, when I compiled FUSE kernel module, it behaves erratically in
> > a way making the FUSE developer think I may have come across the cache
> > coherency bug in arm and mips, fixed sometime around 2.6.17.
> >
> > Since I can not change the kernel that is running, I was looking for
> > alternate solutions. FUSE itself has a work around, that calls
> > flush_cache_page(), but I found that mips-board atlas does not have
> > this defined:
> >
> > fuse: Unknown symbol flush_cache_page
>
> There are cache coherency issues on the 8634.  You should be using the
> vendor's very most recent kernels.  For me they seem to have resolved
> the cache issues.
>
> Also as noted by others, you need the exact kernel sources if you are
> going to build working modules.
>
> David Daney
>
>

Re: MIPS 4KEc with 2.6.15

[Jorgen Lundman]

Yeha I would love to use tangox, but there is none with Linux, at least 
no tarball of the kernel I have found?

Where can I get tangox?

Lund


Mark Lin wrote:
> Jorgen,
> 
> You should not be using the atlas definition.  Try the tangox one instead.
> 
> With the flush_cache_page changes, FUSE works fine for me using 2.6.15
> and Sigma's tango2 board.
> 
> Mark Lin
> 
> On Jan 7, 2008 10:52 AM, David Daney <ddaney@avtrex.com> wrote:
>> Jorgen Lundman wrote:
>>> Hello list,
>>>
>>> I have an embedded device running 2.6.15 kernel on a MIPS 4KEc 300MHz
>>> CPU. It was configured for Sigma's tango2 board, which I know nothing
>>> about, so I picked a mips-board by random, "atlas", and found I can
>>> produce working kernel module compiles.
>>>
>>> However, when I compiled FUSE kernel module, it behaves erratically in
>>> a way making the FUSE developer think I may have come across the cache
>>> coherency bug in arm and mips, fixed sometime around 2.6.17.
>>>
>>> Since I can not change the kernel that is running, I was looking for
>>> alternate solutions. FUSE itself has a work around, that calls
>>> flush_cache_page(), but I found that mips-board atlas does not have
>>> this defined:
>>>
>>> fuse: Unknown symbol flush_cache_page
>> There are cache coherency issues on the 8634.  You should be using the
>> vendor's very most recent kernels.  For me they seem to have resolved
>> the cache issues.
>>
>> Also as noted by others, you need the exact kernel sources if you are
>> going to build working modules.
>>
>> David Daney
>>
>>
> 

-- 
Jorgen Lundman       | <lundman@lundman.net>
Unix Administrator   | +81 (0)3 -5456-2687 ext 1017 (work)
Shibuya-ku, Tokyo    | +81 (0)90-5578-8500          (cell)
Japan                | +81 (0)3 -3375-1767          (home)

Re: MIPS 4KEc with 2.6.15

[David Daney]

Jorgen Lundman wrote:
> Yeha I would love to use tangox, but there is none with Linux, at
> least no tarball of the kernel I have found?
>
> Where can I get tangox?
>
> Lund
>
The Linux kernel is GPL, whoever gave you the board and the kernel
should give you the kernel source.

David Daney

Re: MIPS 4KEc with 2.6.15

[Jorgen Lundman]

Sure, and I agree. We both know how often than happens, or how quickly. 
So, while we hold our breath for that to happen, mean while, I am hoping 
to find the TangoX mips-board details somewhere...




David Daney wrote:
> Jorgen Lundman wrote:
>> Yeha I would love to use tangox, but there is none with Linux, at
>> least no tarball of the kernel I have found?
>>
>> Where can I get tangox?
>>
>> Lund
>>
> The Linux kernel is GPL, whoever gave you the board and the kernel
> should give you the kernel source.
> 
> David Daney
> 
> 

-- 
Jorgen Lundman       | <lundman@lundman.net>
Unix Administrator   | +81 (0)3 -5456-2687 ext 1017 (work)
Shibuya-ku, Tokyo    | +81 (0)90-5578-8500          (cell)
Japan                | +81 (0)3 -3375-1767          (home)

Re: MIPS 4KEc with 2.6.15

[Martin Michlmayr]

* Jorgen Lundman <lundman@lundman.net> [2008-01-10 13:06]:
> Sure, and I agree. We both know how often than happens, or how
> quickly. So, while we hold our breath for that to happen, mean
> while, I am hoping to find the TangoX mips-board details
> somewhere...

If they are not helpful, you could try asking the guys from
http://gpl-violations.org/ for help.
-- 
Martin Michlmayr
http://www.cyrius.com/