drivers - modules versus compiled in?

Kevin B. Hendricks khendricks at
Fri Nov 2 05:11:30 EST 2001


I forgot to include my info:

Kernel 2.4.10-ac6
PowerMac B+W G3 with 512Meg with every pci slot filled
(Adaptec SCSI Card, Radeon 32Meg Mac Edition PCI Card, and an AsanteFast
10/100 NIC (the one I am trying to get to work better).



On November 1, 2001 01:01, Kevin B. Hendricks wrote:
> Hi Dan,
> The driver in question is the tulip nic driver with my modifications to
> support the PNIC_II chip (but most of the driver is common acrosss other
> chips that tulip supports including transmit and receive buffer code,
> which I have not touched)
> The funny thing is that when compiled as a module, it works flawlessly.
> But when I compile it into the kernel, it seems a bit flakey and some
> received packets get lost somehow (I can see the transmitted packets
> generating link activity on the switch, but nothing seems to come the
> other way).  The driver debug messages all look sane and it looks like
> the driver is working but not data is ever returned from the card.
> This driver does use DMA and does allocate buffer space for it.
> Given the "virt_to_bus()' issue you describe, I would expect the
> compiled in kernel to be the working one and not the one built as a
> module.
> Are there any mechanisms that would help isolate a module's memory from
> corruption that don't exist when compiled into a kernel?
> Thanks,
> Kevin
> On November 1, 2001 12:48, you wrote:
> > Kevin B. Hendricks wrote:
> > > Are the allocated memory areas differnt?
> >
> > Yes, this is usually why you may see different behavior.  First,
> > the module itself is allocated from kernel memory that other errant
> > pointers could access that wouldn't otherwise.  Usually, the problem
> > is related to buffers or data structures the driver allocates that
> > are further used for DMA operations.  Things like 'virt_to_bus()'
> > won't work on static objects in a module, while it will in a
> > compiled driver.
> >
> > > Any hints as to what might have changed?
> >
> > Provide some hints to us :-).  What type of system, what
> > kernel, what driver?
> >
> > Thanks.
> >
> >
> > 	-- Dan

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