Re: [PATCH v2 3/4] x86/PCI: Tidy E820 removal messages

Bjorn Helgaas
2022-12-09T20:34:41Z

On Fri, Dec 09, 2022 at 08:42:06PM +0200, Andy Shevchenko wrote:
> On Thu, Dec 08, 2022 at 01:03:40PM -0600, Bjorn Helgaas wrote:
> > From: Bjorn Helgaas <bhelgaas@google.com>
> >
> > These messages:
> >
> > clipped [mem size 0x00000000 64bit] to [mem size 0xfffffffffffa0000 64bit] for e820 entry [mem 0x0009f000-0x000fffff]
> >
> > aren't as useful as they could be because (a) the resource is often
> > IORESOURCE_UNSET, so we print the size instead of the start/end and (b) we
> > print the available resource even if it is empty after removing the E820
> > entry.
> >
> > Print the available space by hand to avoid the IORESOURCE_UNSET problem and
> > only if it's non-empty. No functional change intended.
>
> ...
>
> > + if (avail->end > avail->start)
> > + pr_info("resource: remaining [mem %#010llx-%#010llx] available\n",
> > + (unsigned long long) avail->start,
> > + (unsigned long long) avail->end);
>
> Is there any point why we do not use %pa for resource_size_t parameters?

Only my ignorance :) Thanks for pointing that out; I changed it to
this and added a comment about why:

--- a/arch/x86/kernel/resource.c
+++ b/arch/x86/kernel/resource.c
@@ -42,8 +42,16 @@ static void remove_e820_regions(struct resource *avail)

resource_clip(avail, e820_start, e820_end);
if (orig.start != avail->start || orig.end != avail->end) {
- pr_info("clipped %pR to %pR for e820 entry [mem %#010Lx-%#010Lx]\n",
- &orig, avail, e820_start, e820_end);
+ pr_info("resource: avoiding allocation from e820 entry [mem %#010Lx-%#010Lx]\n",
+ e820_start, e820_end);
+ if (avail->end > avail->start)
+ /*
+ * Use %pa instead of %pR because "avail"
+ * is typically IORESOURCE_UNSET, so %pR
+ * shows the size instead of addresses.
+ */
+ pr_info("resource: remaining [mem %pa-%pa] available\n",
+ &avail->start, &avail->end);
orig = *avail;
}
}