PNP: increase the maximum number of resources

In commit a7839e960675b549f06209d18283d5cee2ce9261 the number of PNP resources was increased. In testing, we've found that the 'exceeded' warnings still get hit with quite high frequency. See https://bugzilla.redhat.com/show_bug.cgi?id=436589
for examples.

I added the debug patch below, which yielded an interesting output.

pnpacpi: exceeded the max number of mem resources. Max:12 Found:12

off by one somewhere ?

Dave

index 6aa231e..0c22e41 100644
@@ -86,7 +86,7 @@ static void pnpacpi_parse_allocated_irqresource(struct pnp_resource_table *res,
 		i++;
 	if (i >= PNP_MAX_IRQ && !warned) {
 		printk(KERN_ERR "pnpacpi: exceeded the max number of IRQ "
-				"resources: %d \n", PNP_MAX_IRQ);
+				"resources. Max:%d Found:%d\n", PNP_MAX_IRQ, i);
 		warned = 1;
 		return;
 	}

@@ -188,7 +188,7 @@ static void pnpacpi_parse_allocated_dmaresource(struct pnp_resource_table *res,
 		res->dma_resource[i].end = dma;
 	} else if (!warned) {
 		printk(KERN_ERR "pnpacpi: exceeded the max number of DMA "
-				"resources: %d \n", PNP_MAX_DMA);
+				"resources. Max:%d Found:%d\n", PNP_MAX_DMA, i);
 		warned = 1;
 	}
 }

@@ -214,7 +214,7 @@ static void pnpacpi_parse_allocated_ioresource(struct pnp_resource_table *res,
 		res->port_resource[i].end = io + len - 1;
 	} else if (!warned) {
 		printk(KERN_ERR "pnpacpi: exceeded the max number of IO "
-				"resources: %d \n", PNP_MAX_PORT);
+				"resources. Max:%d Found:%d\n", PNP_MAX_PORT, i);
 		warned = 1;
 	}
 }

@@ -242,7 +242,7 @@ static void pnpacpi_parse_allocated_memresource(struct pnp_resource_table *res,
 		res->mem_resource[i].end = mem + len - 1;
 	} else if (!warned) {
 		printk(KERN_ERR "pnpacpi: exceeded the max number of mem "
-				"resources: %d\n", PNP_MAX_MEM);
+				"resources. Max:%d Found:%d\n", PNP_MAX_MEM, i);
 		warned = 1;
 	}
 }

http://www.codemonkey.org.uk

No, your patch is just not giving out any additional information. 'i' is the number of currently allocated resources, not the number asked for. That number does not exist anywhere at that point as far as I can see, you'll have to add a counter for it.

That looks valid for every resource type btw.

OG.

In 2.6.23 we had:

#define PNP_MAX_PORT 8
#define PNP_MAX_MEM 4

And the kernel silently ignored a BIOS exceeding these limits

In 2.6.24 we have:

#define PNP_MAX_PORT 40
#define PNP_MAX_MEM 12

And the kernel complains with KERN_ERR when a BIOS has more resources than the kernel can describe within these limits.

We know that there are cases where these static limits will be exceeded but refrained from making these numbers larger due to concern about data structure size and expectation that the majory of systems will fit within these limits. (eg. there was one box with about 96 IO resources)

I agree that having a KERN_ERR that you know is going to fire is not a good situation. We can either delete or KERN_DEBUG the message if it causes support issues -- for we know that <= 2.6.23 did worse by being silent.

Thomas worked on a patch to make resource allocation dynamic and do away with these limits. Unfortunately it was rather large and it wasn't in time for the 2.6.25-rc1 window. So right now we are on a trajectory for 2.6.25 to behave exactly like 2.6.24.
Indeed, I don't think that patch made it into the test tree, so unless we revive that patch, it will miss 2.6.26 as well.

thanks,
-Len

It rather violently broke ISAPnP.

Rene.

...

I had the problem that I could not test on isa systems. Rene Herman helped here a lot.
There are still open issues, last state was (comment from Rene):
------------------------
No. Please note we're talking about ISAPnP, not PnPBIOS. No BIOS involved at all.

Driver (sound/isa/cs423x/cs4236.c) furthermore does not use anything but the PnP layer itself. Start at snd_cs423x_pnpc_detect, which is the pnp .probe() method.

I'll look into providing a more extensive answer and/or test whatever comes in later.
-------------------------
I can also look at this, any hints until then are appreciated.

I also expect Bjorn was bound to other bugs and pushing things in a rush is not good thing anyway.
At the end I asked for a macro problem I only had a rather ugly solution, didn't get an answer (IIRC I also added a compile bug in my suggestions) and things got stuck...

Do you want me to rework the patches, lay out where I see problems and give it another try to get this into -mm?

I am bound to work the next days, but it shouldn't be that much work after all anymore to summarize things and send something (not sure about the ISA things).

Hmm, maybe someone still can give a comment on my last one, it's still valid. I want to check every pnp_{port,mem,irq,dma}_{start,end..} whether they are valid.

This macro does not work:
+#define pnp_port_start(dev,bar) (pnp_port_valid((dev),(bar)) ? (dev)->res.port_resource[(bar)].start \
+ : pnp_dbg("WARN: Port start %d - [%s] invalid - %s:%d", (bar), (dev->name), __FUNCTION__, __LINE__))

The only solution I see is to use small inline functions, but that would blow up include/linux/pnp.h significantly. The idea of the inline functions is stated here:
http://kerneltrap.org/mailarchive/linux-kernel/2008/2/6/743614

The warning can also be omitted (the drivers should have checked for valid already - in theory...), but it should at least stay there at the beginning to find drivers who do not check for valid before accessing pnp_resource_table entries.

Thomas

I'm sorry that I haven't responded to this. I have some reservations, but I wanted to try out some alternate ideas before just being a nay- sayer because usually my grand ideas turn out to have fatal flaws.

My current grand but untested idea is that struct pnp_resource_table is too exposed and should be better abstracted, even inside the PNP subsystem. Since PNP is supposed to be a way to discover platform devices, I'm looking at the platform device interfaces for ideas.

Whatever we do, I think it has to be done incrementally to make it reviewable and bisectable.

Bjorn

Perhaps we can go organize a fundraiser for SuSE so they can go out and buy an ISAPnP soundcard. I have a few I can sell. I promise I won't overcharge them (much).

Did look, but decided there wasn't much more specifically to add. It's something more fundamental about the flow of things and while the comment above is obviously cynical I did grow a bit tired of a series of patches that just transported the OOPS two lines down again each time, so I held out for Bjorn as well.

Still availabe for tests.

Rene.