Re: [Xenomai] mmap when using in conjunction with mapper to retrieve memory mapped IO space

["Pham, Phong" <phamp@ddc-web.com>]

Hi,

Instead of  symbol `mmap' out of range, I now have symbol `malloc' out of range.  I removed  all the -fPIC in my environment.  I have to recompile libc???  I never compiled libc and wants to avoid it.

Any suggestion on
R_PPC_REL24 relocation at 0x0ffacd3c for symbol `mmap/malloc' out of range

is appreciated.

This is after I add LDFLAGS (from xeno-config) during the process of creating a shared library.

Phong.

-----Original Message-----
From: Pham, Phong
Sent: Tuesday, April 17, 2018 7:22 PM
To: 'Philippe Gerum'; xenomai@xenomai.org
Cc: Hillman, Robert
Subject: RE: [Xenomai] mmap when using in conjunction with mapper to retrieve memory mapped IO space


Hi Philippe and all,

Regarding "Your app may be missing symbol wrapping. Please check out this doc:

https://xenomai.org/documentation/xenomai-3/html/xeno3prm/group__cobalt__api.html"

Thanks for the tip.  In the Makefile fragment from this link:
https://xenomai.org/building-applications-with-xenomai-3-x/

I suggest you add the missing --posix in the LDFLAGS as well.  After all, I copied my app from this very snippet and that's why I get the error.

On the same idea (using LDFLAGS from xeno-config), I would like to create a dynamically linked library (.so).  Without the LDFLAGS from xeno-config, my library loads fine (but will fail when mmap is called); with the LDFLAGS that has --posix, I get this error when loading:

R_PPC_REL24 relocation at 0x0ffacd3c for symbol `mmap' out of range

Does this mean I have to recompile all of the Xenomai library with -fPIC?  I didn't see anything regarding that choice during "configure" but peeking into the configure script, there are a few -fPIC occurrences.  Currently, I am using "Building the PPC32 libraries" instruction and also I didn't need to perform ./script/bootstrap b/c I am building it from the release tarball.

$xenomai_root/configure --host=powerpc-linux --with-core=cobalt --enable-debug=symbols

Suggestion on the error above and/or compiling Xenomai library w/ -fPIC is appreciated.

Just fyi w/ regard to your updated "comment fix" on how to mmap(), I don't know if you need to update udd.h (right above struct udd_memregion) as well.  i.e. the same comment exists there but don't know if the comment there is retrieved from the location where you made the "comment fix".

Phong.

-----Original Message-----
From: Philippe Gerum [mailto:rpm@xenomai.org]
Sent: Thursday, April 12, 2018 1:58 AM
To: Pham, Phong; xenomai@xenomai.org
Cc: Hillman, Robert
Subject: Re: [Xenomai] mmap when using in conjunction with mapper to retrieve memory mapped IO space

On 04/10/2018 09:03 PM, Pham, Phong wrote:
>
> Hi,
>
> According to page 651
> https://xenomai.org/documentation/xenomai-3/pdf/xeno3prm.pdf
>
>
> This will make such region accessible via the mapper device using the
> following sequence of code, via the default ->mmap() handler from the UDD core:
> int fd, fdm;
> void *p;
> fd = open("/dev/foocard", O_RDWR);
> fdm = open("/dev/foocard,mapper@2", O_RDWR); p = mmap(NULL, 4096,
> PROT_READ|PROT_WRITE, 0, fdm, 0);
>
>
> I have several questions:
>
> 1)      It looks like the 4th argument of mmap (the one to the left of "fdm") needs to be either MAP_SHARED or MAP_PRIVATE
>
> 2)      The "@" character right after "mapper" is not valid (ie. there should be no "@" character at all)
>
> 3)      /dev/foocard should be /dev/rtdm/foocard


Fixed, thanks.

https://xenomai.org/documentation/xenomai-3/html/xeno3prm/structudd__memregion.html#udd_memory_region

>
> here's my real question:
>
> Assuming all 3 of the above is valid from user space, and on the
> kernel space, I followed the ex. to create memory region, etc. such
> that I do see my device
>
> # ls -l dev/rtdm
> crw-------    1 root     root      252,   0 Jan  1 00:00 autotune
> crw-------    1 root     root      247,   0 Jan  1 00:00 eeprom
> crw-------    1 root     root      246,   0 Jan  1 00:00 eeprom,mapper0
> crw-------    1 root     root      254,   0 Jan  1 00:00 memdev-private
> crw-------    1 root     root      254,   1 Jan  1 00:00 memdev-shared
> crw-------    1 root     root      253,   0 Jan  1 00:00 memdev-sys
> crw-------    1 root     root      249,   0 Jan  1 00:00 mmio
> crw-------    1 root     root      248,   0 Jan  1 00:00 mmio,mapper0
> crw-------    1 root     root      248,   1 Jan  1 00:00 mmio,mapper1
> crw-------    1 root     root      248,   2 Jan  1 00:00 mmio,mapper2
> crw-------    1 root     root      248,   3 Jan  1 00:00 mmio,mapper3
> crw-------    1 root     root      248,   4 Jan  1 00:00 mmio,mapper4
> crw-------    1 root     root      250,   0 Jan  1 00:00 switchtest
> crw-------    1 root     root      251,   0 Jan  1 00:00 timerbench
>
>
> like /dev/rtdm/eeprom and /dev/rtdm/eeprom,mapper0  etc. I don't see
> my kernel hook ever gets called
>
>
> static struct udd_device eeprom = {
>               .device_flags = RTDM_NAMED_DEVICE,
>               .device_name = "eeprom",
>               .ops = {
>                              .close = phong_scs750_close,
>                              .open = phong_scs750_open,
>                              .mmap = phong_scs750_mmap,
>               }
>
> By that, I mean phong_scs750_open, phong_scs750_mmap never gets invoked.  mmap() from user space returns -1 with errno value of 19 (ENODEV).  Any advise?

Your app may be missing symbol wrapping. Please check out this doc:

https://xenomai.org/documentation/xenomai-3/html/xeno3prm/group__cobalt__api.html


--
Philippe.
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