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Message-Id: <1213993734.31598.27.camel@promb-2n-dhcp368.eng.vmware.com>
Date: Fri, 20 Jun 2008 13:28:54 -0700
From: Alok Kataria <akataria@...are.com>
To: Yinghai Lu <yhlu.kernel@...il.com>
Cc: Ingo Molnar <mingo@...e.hu>, "Brown, Len" <len.brown@...el.com>,
Andrew Morton <akpm@...ux-foundation.org>,
"linux-acpi@...r.kernel.org" <linux-acpi@...r.kernel.org>,
LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 1/2] cleanup e820_setup_gap
On Fri, 2008-06-20 at 12:50 -0700, Yinghai Lu wrote:
> On Fri, Jun 20, 2008 at 12:38 PM, Alok Kataria <akataria@...are.com> wrote:
> > Here is the patch based on tip/master
> >
> > Please have a look
> >
> > --
> >
> > This is a preparatory patch for the next patch in series.
> > Moves some code from e820_setup_gap to a new function e820_search_gap.
> > This patch is a part of a bug fix where we walk the ACPI table to calculate
> > a gap for PCI optional devices.
> >
> > Signed-off-by: Alok N Kataria <akataria@...are.com>
> >
> > Index: linux-trees.git/arch/x86/kernel/e820.c
> > ===================================================================
> > --- linux-trees.git.orig/arch/x86/kernel/e820.c 2008-06-20 10:32:44.000000000 -0700
> > +++ linux-trees.git/arch/x86/kernel/e820.c 2008-06-20 12:27:58.000000000 -0700
> > @@ -442,26 +442,22 @@
> > }
> >
> > /*
> > - * Search for the biggest gap in the low 32 bits of the e820
> > - * memory space. We pass this space to PCI to assign MMIO resources
> > - * for hotplug or unconfigured devices in.
> > - * Hopefully the BIOS let enough space left.
> > + * Search for a gap in the e820 memory space from start_addr to 2^32.
> > */
> > -__init void e820_setup_gap(void)
> > +__init int e820_search_gap(unsigned long *gapstart, unsigned long *gapsize,
> > + unsigned long start_addr)
> > {
> > - unsigned long gapstart, gapsize, round;
> > - unsigned long long last;
> > - int i;
> > + unsigned long last = 0x100000000ull;
>
> why changing "unsigned long long" to "unsigned long" ?
> it will overflow on 32bit
>
Oops...my bad, it was unsigned long in e820_64.c. Should be more careful
with these cross ports.
Thanks for catching it.
--
This is a preparatory patch for the next patch in series.
Moves some code from e820_setup_gap to a new function e820_search_gap.
This patch is a part of a bug fix where we walk the ACPI table to calculate
a gap for PCI optional devices.
Signed-off-by: Alok N Kataria <akataria@...are.com>
Index: linux-trees.git/arch/x86/kernel/e820.c
===================================================================
--- linux-trees.git.orig/arch/x86/kernel/e820.c 2008-06-20 10:32:44.000000000 -0700
+++ linux-trees.git/arch/x86/kernel/e820.c 2008-06-20 13:23:32.000000000 -0700
@@ -442,26 +442,22 @@
}
/*
- * Search for the biggest gap in the low 32 bits of the e820
- * memory space. We pass this space to PCI to assign MMIO resources
- * for hotplug or unconfigured devices in.
- * Hopefully the BIOS let enough space left.
+ * Search for a gap in the e820 memory space from start_addr to 2^32.
*/
-__init void e820_setup_gap(void)
+__init int e820_search_gap(unsigned long *gapstart, unsigned long *gapsize,
+ unsigned long start_addr)
{
- unsigned long gapstart, gapsize, round;
- unsigned long long last;
- int i;
+ unsigned long long last = 0x100000000ull;
+ int i = e820.nr_map;
int found = 0;
- last = 0x100000000ull;
- gapstart = 0x10000000;
- gapsize = 0x400000;
- i = e820.nr_map;
while (--i >= 0) {
unsigned long long start = e820.map[i].addr;
unsigned long long end = start + e820.map[i].size;
+ if (end < start_addr)
+ continue;
+
/*
* Since "last" is at most 4GB, we know we'll
* fit in 32 bits if this condition is true
@@ -469,15 +465,32 @@
if (last > end) {
unsigned long gap = last - end;
- if (gap > gapsize) {
- gapsize = gap;
- gapstart = end;
+ if (gap >= *gapsize) {
+ *gapsize = gap;
+ *gapstart = end;
found = 1;
}
}
if (start < last)
last = start;
}
+ return found;
+}
+
+/*
+ * Search for the biggest gap in the low 32 bits of the e820
+ * memory space. We pass this space to PCI to assign MMIO resources
+ * for hotplug or unconfigured devices in.
+ * Hopefully the BIOS let enough space left.
+ */
+__init void e820_setup_gap(void)
+{
+ unsigned long gapstart, gapsize, round;
+ int found;
+
+ gapstart = 0x10000000;
+ gapsize = 0x400000;
+ found = e820_search_gap(&gapstart, &gapsize, 0);
#ifdef CONFIG_X86_64
if (!found) {
Index: linux-trees.git/include/asm-x86/e820.h
===================================================================
--- linux-trees.git.orig/include/asm-x86/e820.h 2008-06-20 10:32:44.000000000 -0700
+++ linux-trees.git/include/asm-x86/e820.h 2008-06-20 12:18:40.000000000 -0700
@@ -69,6 +69,8 @@
unsigned new_type);
extern void update_e820(void);
extern void e820_setup_gap(void);
+extern int e820_search_gap(unsigned long *gapstart, unsigned long *gapsize,
+ unsigned long start_addr);
struct setup_data;
extern void parse_e820_ext(struct setup_data *data, unsigned long pa_data);
--
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