I may not have followed up, but my problem was traced to permissions on a subdirectory I think I had created on the disk
 being mounted (maybe /usr/lib?). In any case, I did find it, adjusted (maybe I had the wrong owner?) and it fixed the 
login issues. It would be great if the source of the problem were logged somewhere so it would be easier to fix!

> On Apr 4, 2021, at 11:47 PM, Geoff Roberts(deleted) <community-noreply@qnx.com> wrote:
> 
> I am having a similar problem with the 7.1 RPi4 and Xilinx ZCU-102. Maybe a "senior's" moment"?
> 
> I need to add/change passwords but executing passwd results in the following message:
> 
> passwd: System error
> 
> On the RPi4 I added the "mntperms=755" to the SDMMC driver as per the use message:
> 
> devb-sdmmc-bcm2711 mem name=below1G sdio addr=0xfe340000,irq=158,bs=bmstr_base=0xc0000000 disk name=sd blk mntperms=
755
> 
> But this has no effect. Nothing I try works.
> 
> use devb-sdmmc-bcm2711 indicates that io-blk (blk) options are supported. But a pidin shows no io-blk? The SDMMC 
driver details are missing from the RPi4 BSP User Guide and I can't find anything meaningful in the source to the SDMMC 
driver.
> 
> I tried manually making the paths to /etc/pam.d non-world or group write access (chmod 755) but this didn't work 
either.
> 
> I am using the default /etc/pam.d/[files].  libpam.so is present.
> 
> Am I missing something simple? If so, what?? :-)  This is driving me nuts...
> 
> Apart from this the SDMMC driver seems to work fine. On startup I execute the following mount command to point root '/
' to a QNX6 partition on the SD card:
> 
> mount -t qnx6 /dev/sd0t177 /     and this seems to be OK.
> 
> Thanks,
> 
> Geoff.
> 
>> Thank you!  That seems to have fixed my problem.  (Not sure if this could have
>> been in the release notes, I did look over but didn’t notice.)
>> 
>> I really appreciate your quick response.
>> 
>> -David
>> 
>>>> On Dec 18, 2020, at 5:11 PM, Roger Maclean <community-noreply@qnx.com> wrote:
>>> 
>>> You might be being affected by a change to libpam. PAM requires that the 
>> chain of directories leading up to its config files and modules do not have 
>> group or world write access. It inexplicably omitted the root directory until 
>> recently.
>>> 
>>> Assuming this is the case, you need to add 'mntperms=755' as an option to 
>> the command you use for mounting your file system.
>>> 
>>> 
>>> 
>>> 
>>> _______________________________________________
>>> 
>>> OSTech
>>> http://community.qnx.com/sf/go/post121156
>>> To cancel your subscription to this discussion, please e-mail ostech-core_os
>> -unsubscribe@community.qnx.com
>> 
> 
> 
> 
> 
> 
> 
> _______________________________________________
> 
> OSTech
> http://community.qnx.com/sf/go/post121363
> To cancel your subscription to this discussion, please e-mail ostech-core_os-unsubscribe@community.qnx.com

It is fairly finicky though the rules are fairly straightforward. All config files and dlls used by PAM must be owned by
 root and not be group/writable writable. This must also be true of the directory these are contained in, their parent 
directory etc down to the root.

You might be able to get more information by running slog2info after running into a problem. You might be able to get 
even more by setting the environment variable OPENPAM_DEBUG (to anything) and then looking in slog2 (the environment 
variable has to be set for the process that is trying to use PAM, e.g. su). I don't know when these things were added so
 they may or may not work for you.