Re: Problem with the serial port in Fedora Core 6 -xen kernel

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Gene Heskett wrote:
On Saturday 11 November 2006 19:42, Craig White wrote:

----
you're detective work notwithstanding, Bill Nottingham's suggestion to
put an entry into 'udev' rules was the suggested recommendation for the
problem but since you didn't try that with the xen kernel, didn't post
your results on this bugzilla entry after trying the recommended entry,
I guess none of us will ever be certain.

Someone with the Xen kernel version should be able to repeat this without any problem. It sounds like virtual devices are being created but real devices are not, such as serial ports.


And what sort of an entry might that be? It does create 4 devices now, as its written to do, but the devices are worthless when the onboard hardware hasn't been detected.

Since xen is a category on the installer if you choose to install virtualization, many other people have installed the xen kernel and were caught with real hardware problems. Devices effected on my hearing were video problems, lockups and now serial communication ports.


I guess I am glad that the non-xen kernel gives you what you wanted
after all (the serial port interfaces for your X11). I just assumed that
you chose the xen kernel with the intent to run xen virtualization, but
I am guessing that your motherboard doesn't support xen which is
probably the cause of the problem in the first place.

Isn't XEN restrained to a file, has no hardware unless setup to use real hardware? I am not sure about xen and machine capability but I know that my laptop with sufficient memory would stay railed at full speed and would not last very long with this condition. Also, on other computers the system memory is so low that xen would not work properly. It sounds like the problem that happened to Gene and others is even thinking that the xen version of the kernel would interfere with the operation of their computer. The thought of users was probably that they would try out virtualization at a later date. No user would suspect problems until they tried to setup virtualization,


Either way (I didn't choose it, anaconda did), and I have NDI if this biostar mobo supports xen or not, there has been precious little discussions about it on the 50+ mailing lists I lurk on.

I believe memory requirements are 256 MB per domain that you setup. I cannot recall if it is a requirement for a GUI virtual system or text based systems. I have not used xen myself. I used vmware before but believe they are with different goals and regard the hardware differently.

Now I agree with you that getting rid of the xen kernel solves this
problem. I don't agree with you a bit that it wasn't a udev problem
because if you again read Comment #5 on the above referenced bugzilla
entry, it is obvious that Bill Nottingham believes it is a udev related
problem.

I still don't see what, if anything, udev could do about it when the hardware has not been detected. Does it have some sort of a magic twanger for that case that we common mortals don't know about? I'm now looking at that #5 comment, but have no clue because theres no preamble describing where to put those commands, which I assume would go in /.etc/udev/rules.d/50-udev.rules, but it contains no similar rules. Those in the know will I assume know where in that file, but to me thats not a usable fix without the whole story. But with some use of a figurative shovel to dig a little deeper it seems to indicate it should be added into /etc/udev/rules.d/05-udev-early-rules. It would be more at home there by far.

Is this correct?


Don't know but one would think that serial devices like com ports were recognized and initialized by the common standards for serial ports.

There is a second reason I didn't pursue that angle, any attempt to modprobe anything 8250 related failed due to undefined labels in the module(s). Which brings me back to square one, what can udev do about it when the kernel can't find the hardware in the first place? Heck, right now, with them running, an lspci -vv doesn't show them. Whether they should show I don't recall. I just checked on my firewall box, and they don't appear there either, so perhaps I'm using the wrong tool.

When one installs virtualization, the kernel for xen should not be the default kernel. A normal kernel should also be installed and set to default.


Sorry I'm so dense in your opinion. If it will make you feel better, I'll plead oldtimers since I had a birthday last month, having made it to 72.

Your age is in close proximity to my parents and both seem to have their faculties still. Happy belated BD.

Jim


Craig



--
I have a theory that it's impossible to prove anything, but I can't prove it.


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