* [Xenomai] rtdm_iomap_to_user caching followup
@ 2014-08-20 14:46 Jeffrey Melville
2014-08-20 19:09 ` Gilles Chanteperdrix
0 siblings, 1 reply; 3+ messages in thread
From: Jeffrey Melville @ 2014-08-20 14:46 UTC (permalink / raw)
To: xenomai
All,
There was a patch applied back in January 2013 to disable caching with
memory areas mapped with rtdm_iomap_to_user.
(http://www.xenomai.org/pipermail/xenomai/2013-January/027370.html)
Henri Roosen followed up in September 2013 to say that he still saw
caching behavior with rtdm_iomap_to_user. The original patch didn't
cover the ifdef LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,16) &&
defined(CONFIG_MMU). He submitted two patch options but I didn't see any
responses.
(http://www.xenomai.org/pipermail/xenomai/2013-September/029211.html)
I'm currently working with a Zynq ZC706, using Xenomai 2.6.3 on top of
the Xilinx fork of the 3.8 kernel, as described in the README. The FPGA
guys gave me a test FPGA image with a (dumb) AXI slave that has a very
small register space. Pulling a cache line actually overflows the
register space and causes the bus to lock up. I added a logic analyzer
block to the FPGA to confirm the access addresses.
More importantly, I don't want any of that address space cached even
when the register space gets bigger. I was able to fix my problems by
changing this line:
- remap_pfn_range(vma,from,(to) >> PAGE_SHIFT,size,prot); \
+ remap_pfn_range(vma,from,(to) >>
PAGE_SHIFT,size,pgprot_noncached(prot)); \
Can we apply the patch? I can provide a new one if it is lost. Or is
there a better way to use rtdm_iomap_to_user that lets the caller
specify caching behavior? I couldn't find one.
As a side note, has anyone successfully used Xenomai with Zynq on
kernels newer than 3.8? I haven't found any newer pre/post patches and
haven't had time to play around with manually merging it yet. I'd be
willing to help if this is an area of need.
Cheers,
Jeff
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [Xenomai] rtdm_iomap_to_user caching followup
2014-08-20 14:46 [Xenomai] rtdm_iomap_to_user caching followup Jeffrey Melville
@ 2014-08-20 19:09 ` Gilles Chanteperdrix
2014-08-27 20:59 ` Jeffrey Melville
0 siblings, 1 reply; 3+ messages in thread
From: Gilles Chanteperdrix @ 2014-08-20 19:09 UTC (permalink / raw)
To: Jeffrey Melville, xenomai
On 08/20/2014 04:46 PM, Jeffrey Melville wrote:
> All,
>
> There was a patch applied back in January 2013 to disable caching with
> memory areas mapped with rtdm_iomap_to_user.
> (http://www.xenomai.org/pipermail/xenomai/2013-January/027370.html)
>
> Henri Roosen followed up in September 2013 to say that he still saw
> caching behavior with rtdm_iomap_to_user. The original patch didn't
> cover the ifdef LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,16) &&
> defined(CONFIG_MMU). He submitted two patch options but I didn't see any
> responses.
> (http://www.xenomai.org/pipermail/xenomai/2013-September/029211.html)
I believe this has been merged with commit
http://git.xenomai.org/xenomai-2.6.git/commit/?id=1b8fb14e486ac0604e44067a0f1f89dc14153e95
Could you try xenomai 2.6 git to see if you still have the issue?
--
Gilles.
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [Xenomai] rtdm_iomap_to_user caching followup
2014-08-20 19:09 ` Gilles Chanteperdrix
@ 2014-08-27 20:59 ` Jeffrey Melville
0 siblings, 0 replies; 3+ messages in thread
From: Jeffrey Melville @ 2014-08-27 20:59 UTC (permalink / raw)
To: xenomai
On 8/20/2014 3:09 PM, Gilles Chanteperdrix wrote:
> On 08/20/2014 04:46 PM, Jeffrey Melville wrote:
>> All,
>>
>> There was a patch applied back in January 2013 to disable caching with
>> memory areas mapped with rtdm_iomap_to_user.
>> (http://www.xenomai.org/pipermail/xenomai/2013-January/027370.html)
>>
>> Henri Roosen followed up in September 2013 to say that he still saw
>> caching behavior with rtdm_iomap_to_user. The original patch didn't
>> cover the ifdef LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,16) &&
>> defined(CONFIG_MMU). He submitted two patch options but I didn't see any
>> responses.
>> (http://www.xenomai.org/pipermail/xenomai/2013-September/029211.html)
>
>
> I believe this has been merged with commit
> http://git.xenomai.org/xenomai-2.6.git/commit/?id=1b8fb14e486ac0604e44067a0f1f89dc14153e95
>
> Could you try xenomai 2.6 git to see if you still have the issue?
>
Gilles,
Thanks for your response. My mistake, I thought I had already looked at
the 2.6 git head. The commit you mentioned is the right one. I tested
the 2.6 git on my hardware and didn't have any lockup issues. Yocto
actually still mistakenly applied my old patch against the kmem wrapper
(which I'm not using anywhere). I need to remove that from my build but
otherwise everything looks good for now.
Cheers,
Jeff
^ permalink raw reply [flat|nested] 3+ messages in thread
end of thread, other threads:[~2014-08-27 20:59 UTC | newest]
Thread overview: 3+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2014-08-20 14:46 [Xenomai] rtdm_iomap_to_user caching followup Jeffrey Melville
2014-08-20 19:09 ` Gilles Chanteperdrix
2014-08-27 20:59 ` Jeffrey Melville
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.