Re: [Xenomai-help] FW: rtdm_iomap_to_user() I-pipe error

["Asier Tamayo" <asier.tamayo@domain.hid>]

Hello,

Thanks for your help. 

I know my Xenomai version is quite out of date. However, as I'm using the ELinOS distribution (which already has its own patches), I find it really difficult to upgrade to Xenomai 2.4.10. Anyway, I can apply changes to some files. 

The rtdm_iomap_to_user function is referenced in drvlib.c and rtdm_driver.h: I compare the 2.4.7 and 2.4.10 versions and they are almost identical, so I think there will be no use in patching the kernel for these 2 files. Do you know of any other file that could make any difference in my problem? 

If I compare versions 2.4.7 and 2.5.6 (the last one) of Xenomai, I can see the last version uses "/dev/rtheap" instead of "/dev/zero" and that there are some changes if CONFIG_MMU is not defined. My system (Intel Atom N270 CPU) is configured with MMU and therefore the only actual changes between the versions are regarding "dev/rtheap". Does it make any difference? Xenomai 2.4.7 has "/dev/rtpheap" but no "/dev/rtheap"; should I use it instead of "/dev/zero"?


> > virt_to_phys(new_iomap) --> 0xf5f6f000 
> 
> virt_to_phys is not supposed to work in that case. Since you ioremap'ed
> the address, you already know the physical address anyway.
> 
Is there any function that will tell me the real physical address in order to make sure the mapping is correct?

Again, thanks for your help.

Best regards,

Asier


> -----Original Message-----
> From: Gilles Chanteperdrix [mailto:gilles.chanteperdrix@xenomai.org]
> Sent: Tuesday, April 26, 2011 1:15 PM
> To: Asier Tamayo
> Cc: Jan Kiszka; xenomai-help@gna.org
> Subject: Re: [Xenomai-help] FW: rtdm_iomap_to_user() I-pipe error
> 
> 
> Asier Tamayo wrote:
> > Hello again,
> > 
> > When one doesn't get replies to his questions, it may be either
> > because: i) they are too obvious (RTFM), ii) too difficult, iii)
> > there is little information and it makes the checking in 
> one's system
> > impossible, or iv) they haven't been correctly explained. 
> It may also
> > be that the help demander is not being polite.
> > 
> > As i have received no answer, I will assume I haven't explained my
> > problem correctly and will give myself a second chance ;) The
> > following lines will just rewrite my question, since I haven't been
> > able to find any new clue:
> > 
> > I'm porting a PCI driver to a RTDM, using Xenomai version 2.4.7 and
> > Linux 2.6.27, from the ELinOS 5.0 distribution.
> 
> Before anything else, please try the latest version of the branch you
> use (that would be Xenomai 2.4.10)
> 
> > 
> > I want to allow a RT task to access the PCI memory directly, by
> > calling the rtdm_iomap_to_user() function just after mlockall and
> > rt_dev_open, and before rt_task_shadow. The function returns me a
> > correct value, but then I cannot access the PCI registers by using
> > that address. The mmap seems not to be correct. The values I get:
> > 
> > Driver: xen_mydriver->location = pci_resource_start(dev,0); -->
> > 0x20000000 xen_mydriver->base_address =
> > ioremap(xen_mydriver->location, xen_mydriver->mem_size); -->
> > 0xe0a00000 *(unsigned short*)(my_context->base_address + 0x100) =
> > 0xAAAA; --> It works
> > 
> > RT task: rtdm_iomap_to_user(user_info,my_context->location, 300,
> > PROT_READ|PROT_WRITE, &new_iomap, NULL, NULL); --> 0xb5f6f000 
> > virt_to_phys(new_iomap) --> 0xf5f6f000 *(unsigned 
> short*)(new_iomap +
> 
> virt_to_phys is not supposed to work in that case. Since you 
> ioremap'ed
> the address, you already know the physical address anyway.
> 
> -- 
>                                                               
>   Gilles.
>