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Subject[PATCH] x86-64: improve e820_search_gap()
Blindly putting the gap close after max_pfn might be fine for native
(though even there I'm uncertain regarding memory hotplug), but will
certainly present a problem on Xen. And properly searching for a gap
above 4Gb shouldn't hurt native.

Also, make the function static to ensure there are no other users that
could depend on the previous behavior regarding the way start_addr gets
specified.

Signed-off-by: Jan Beulich <jbeulich@novell.com>
Cc: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>

---
arch/x86/include/asm/e820.h | 2 --
arch/x86/kernel/e820.c | 11 +++++++++--
2 files changed, 9 insertions(+), 4 deletions(-)

--- linux-2.6.29-rc7/arch/x86/include/asm/e820.h 2009-03-11 17:52:10.000000000 +0100
+++ 2.6.29-rc7-x86_64-e820-setup-gap-64bit/arch/x86/include/asm/e820.h 2009-03-06 11:25:35.000000000 +0100
@@ -79,8 +79,6 @@ extern u64 e820_remove_range(u64 start,
int checktype);
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, unsigned long long end_addr);
struct setup_data;
extern void parse_e820_ext(struct setup_data *data, unsigned long pa_data);

--- linux-2.6.29-rc7/arch/x86/kernel/e820.c 2009-03-11 17:52:10.000000000 +0100
+++ 2.6.29-rc7-x86_64-e820-setup-gap-64bit/arch/x86/kernel/e820.c 2009-03-06 11:24:34.000000000 +0100
@@ -533,13 +533,19 @@ static void __init update_e820_saved(voi
/*
* Search for a gap in the e820 memory space from start_addr to end_addr.
*/
-__init int e820_search_gap(unsigned long *gapstart, unsigned long *gapsize,
+static int __init
+e820_search_gap(unsigned long *gapstart, unsigned long *gapsize,
unsigned long start_addr, unsigned long long end_addr)
{
unsigned long long last;
int i = e820.nr_map;
int found = 0;

+#ifdef CONFIG_X86_64
+ if (start_addr >= MAX_GAP_END)
+ last = end_addr ?: (1UL << boot_cpu_data.x86_phys_bits);
+ else
+#endif
last = (end_addr && end_addr < MAX_GAP_END) ? end_addr : MAX_GAP_END;

while (--i >= 0) {
@@ -585,11 +591,12 @@ __init void e820_setup_gap(void)

#ifdef CONFIG_X86_64
if (!found) {
- gapstart = (max_pfn << PAGE_SHIFT) + 1024*1024;
printk(KERN_ERR "PCI: Warning: Cannot find a gap in the 32bit "
"address range\n"
KERN_ERR "PCI: Unassigned devices with 32bit resource "
"registers may break!\n");
+ found = e820_search_gap(&gapstart, &gapsize, MAX_GAP_END, 0);
+ BUG_ON(!found);
}
#endif





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