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Re: spca5xx freezes system



It took me a month, but I finally found time to build a 2.6.16 kernel
with FC5's gcc32, and I confirmed that this does workaround the
problem.  I emailed the developer of spca5xx about this, and this was
his reply:
######
People report crash when the kernel is configured with a 4ko stack
CONFIG_4KSTACKS
you should never set this, the jpeg decoder inside the spca5xx module need a
8ko stack.
People report crash with FC5 and gcc 4.1, setting in the Makefile this option
for CFLAGS fix the problem
-fno-unit-at-a-time
I am using OpenSuse set with 2.6.16 and gcc 4.1 without any problem
#####

I also tested his -fno-unit-at-a-time workaround, and it made no
difference for me.  His requirement of having an 8K stack seems
ridiculous to me.  This is a webcam driver, it shouldn't need an 8k
stack, especially since no others in the kernel have that requirement.

On 4/18/06, D. Hugh Redelmeier <hugh mimosa com> wrote:
| From: Lonni J Friedman <netllama gmail com>

| I couldn't even find such a list on the spca5xx website.  If you've
| got a pointer, I'll gladly take the discussion there.

Well, you can wander around from the links I posted.  They are from
the SourceForge site for the project.  The home page on the site
mentions the mailing list (and an IRC channel).

http://sourceforge.net/mail/?group_id=28498

| I wouldn't be building a Fedora kernel, I'd be building a kernel.org
| kernel, which most definitely is qualified against gcc versions
| earlier than 4.x.  But I do see your point.

I'm a chicken.  I have no idea whether things break if you use a
kernel.org kernel with FC5.

Each of us has our own way to get to a goal.  I'm fairly knowledgeable
about C and C compilers, so I'd try to isolate the bug myself.  Given
that the developer seems reluctant to do so.

On the other hand, your approach is good in that it gives the
developer what he is asking for.

| Well sure, but since the spca5xx developer said that he thought
| gcc-4.x was the problem, I figured it would be a better use of my time
| to not spend time on gcc-4.x, and isolate whether the version of gcc
| that the spca5xx dev claims is 'good' truly is.

My suspicion was what I described: new GCC4 optimizations expose bugs
in the driver.  My path would get to that sooner.

But a quick glance at the list suggests that there are other problems
with the driver.  Your approach would more quickly reveal the problem
if it were device-dependent.


--
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
L. Friedman                                    netllama gmail com
LlamaLand                       http://netllama.linux-sxs.org


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