mirror of
https://github.com/torvalds/linux
synced 2024-11-05 18:23:50 +00:00
a2c606d53a
This prevents allocation of the last 2MB before 4GB. The experiment described here shows Windows 7 ignoring the last 1MB: https://bugzilla.kernel.org/show_bug.cgi?id=23542#c27 This patch ignores the top 2MB instead of just 1MB because H. Peter Anvin says "There will be ROM at the top of the 32-bit address space; it's a fact of the architecture, and on at least older systems it was common to have a shadow 1 MiB below." Acked-by: H. Peter Anvin <hpa@zytor.com> Signed-off-by: Bjorn Helgaas <bjorn.helgaas@hp.com> Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>
48 lines
1 KiB
C
48 lines
1 KiB
C
#include <linux/ioport.h>
|
|
#include <asm/e820.h>
|
|
|
|
static void resource_clip(struct resource *res, resource_size_t start,
|
|
resource_size_t end)
|
|
{
|
|
resource_size_t low = 0, high = 0;
|
|
|
|
if (res->end < start || res->start > end)
|
|
return; /* no conflict */
|
|
|
|
if (res->start < start)
|
|
low = start - res->start;
|
|
|
|
if (res->end > end)
|
|
high = res->end - end;
|
|
|
|
/* Keep the area above or below the conflict, whichever is larger */
|
|
if (low > high)
|
|
res->end = start - 1;
|
|
else
|
|
res->start = end + 1;
|
|
}
|
|
|
|
static void remove_e820_regions(struct resource *avail)
|
|
{
|
|
int i;
|
|
struct e820entry *entry;
|
|
|
|
for (i = 0; i < e820.nr_map; i++) {
|
|
entry = &e820.map[i];
|
|
|
|
resource_clip(avail, entry->addr,
|
|
entry->addr + entry->size - 1);
|
|
}
|
|
}
|
|
|
|
void arch_remove_reservations(struct resource *avail)
|
|
{
|
|
/* Trim out BIOS areas (low 1MB and high 2MB) and E820 regions */
|
|
if (avail->flags & IORESOURCE_MEM) {
|
|
if (avail->start < BIOS_END)
|
|
avail->start = BIOS_END;
|
|
resource_clip(avail, BIOS_ROM_BASE, BIOS_ROM_END);
|
|
|
|
remove_e820_regions(avail);
|
|
}
|
|
}
|