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-rw-r--r--arch/x86/boot/memory.c108
1 files changed, 52 insertions, 56 deletions
diff --git a/arch/x86/boot/memory.c b/arch/x86/boot/memory.c
index 5054c2ddd1a0..cae3feb1035e 100644
--- a/arch/x86/boot/memory.c
+++ b/arch/x86/boot/memory.c
@@ -17,43 +17,41 @@
#define SMAP 0x534d4150 /* ASCII "SMAP" */
-struct e820_ext_entry {
- struct e820entry std;
- u32 ext_flags;
-} __attribute__((packed));
-
static int detect_memory_e820(void)
{
int count = 0;
- u32 next = 0;
- u32 size, id, edi;
- u8 err;
+ struct biosregs ireg, oreg;
struct e820entry *desc = boot_params.e820_map;
- static struct e820_ext_entry buf; /* static so it is zeroed */
+ static struct e820entry buf; /* static so it is zeroed */
+
+ initregs(&ireg);
+ ireg.ax = 0xe820;
+ ireg.cx = sizeof buf;
+ ireg.edx = SMAP;
+ ireg.di = (size_t)&buf;
/*
- * Set this here so that if the BIOS doesn't change this field
- * but still doesn't change %ecx, we're still okay...
+ * Note: at least one BIOS is known which assumes that the
+ * buffer pointed to by one e820 call is the same one as
+ * the previous call, and only changes modified fields. Therefore,
+ * we use a temporary buffer and copy the results entry by entry.
+ *
+ * This routine deliberately does not try to account for
+ * ACPI 3+ extended attributes. This is because there are
+ * BIOSes in the field which report zero for the valid bit for
+ * all ranges, and we don't currently make any use of the
+ * other attribute bits. Revisit this if we see the extended
+ * attribute bits deployed in a meaningful way in the future.
*/
- buf.ext_flags = 1;
do {
- size = sizeof buf;
-
- /* Important: %edx and %esi are clobbered by some BIOSes,
- so they must be either used for the error output
- or explicitly marked clobbered. Given that, assume there
- is something out there clobbering %ebp and %edi, too. */
- asm("pushl %%ebp; int $0x15; popl %%ebp; setc %0"
- : "=d" (err), "+b" (next), "=a" (id), "+c" (size),
- "=D" (edi), "+m" (buf)
- : "D" (&buf), "d" (SMAP), "a" (0xe820)
- : "esi");
+ intcall(0x15, &ireg, &oreg);
+ ireg.ebx = oreg.ebx; /* for next iteration... */
/* BIOSes which terminate the chain with CF = 1 as opposed
to %ebx = 0 don't always report the SMAP signature on
the final, failing, probe. */
- if (err)
+ if (oreg.eflags & X86_EFLAGS_CF)
break;
/* Some BIOSes stop returning SMAP in the middle of
@@ -61,66 +59,64 @@ static int detect_memory_e820(void)
screwed up the map at that point, we might have a
partial map, the full map, or complete garbage, so
just return failure. */
- if (id != SMAP) {
+ if (oreg.eax != SMAP) {
count = 0;
break;
}
- /* ACPI 3.0 added the extended flags support. If bit 0
- in the extended flags is zero, we're supposed to simply
- ignore the entry -- a backwards incompatible change! */
- if (size > 20 && !(buf.ext_flags & 1))
- continue;
-
- *desc++ = buf.std;
+ *desc++ = buf;
count++;
- } while (next && count < ARRAY_SIZE(boot_params.e820_map));
+ } while (ireg.ebx && count < ARRAY_SIZE(boot_params.e820_map));
return boot_params.e820_entries = count;
}
static int detect_memory_e801(void)
{
- u16 ax, bx, cx, dx;
- u8 err;
+ struct biosregs ireg, oreg;
- bx = cx = dx = 0;
- ax = 0xe801;
- asm("stc; int $0x15; setc %0"
- : "=m" (err), "+a" (ax), "+b" (bx), "+c" (cx), "+d" (dx));
+ initregs(&ireg);
+ ireg.ax = 0xe801;
+ intcall(0x15, &ireg, &oreg);
- if (err)
+ if (oreg.eflags & X86_EFLAGS_CF)
return -1;
/* Do we really need to do this? */
- if (cx || dx) {
- ax = cx;
- bx = dx;
+ if (oreg.cx || oreg.dx) {
+ oreg.ax = oreg.cx;
+ oreg.bx = oreg.dx;
}
- if (ax > 15*1024)
+ if (oreg.ax > 15*1024) {
return -1; /* Bogus! */
-
- /* This ignores memory above 16MB if we have a memory hole
- there. If someone actually finds a machine with a memory
- hole at 16MB and no support for 0E820h they should probably
- generate a fake e820 map. */
- boot_params.alt_mem_k = (ax == 15*1024) ? (dx << 6)+ax : ax;
+ } else if (oreg.ax == 15*1024) {
+ boot_params.alt_mem_k = (oreg.dx << 6) + oreg.ax;
+ } else {
+ /*
+ * This ignores memory above 16MB if we have a memory
+ * hole there. If someone actually finds a machine
+ * with a memory hole at 16MB and no support for
+ * 0E820h they should probably generate a fake e820
+ * map.
+ */
+ boot_params.alt_mem_k = oreg.ax;
+ }
return 0;
}
static int detect_memory_88(void)
{
- u16 ax;
- u8 err;
+ struct biosregs ireg, oreg;
- ax = 0x8800;
- asm("stc; int $0x15; setc %0" : "=bcdm" (err), "+a" (ax));
+ initregs(&ireg);
+ ireg.ah = 0x88;
+ intcall(0x15, &ireg, &oreg);
- boot_params.screen_info.ext_mem_k = ax;
+ boot_params.screen_info.ext_mem_k = oreg.ax;
- return -err;
+ return -(oreg.eflags & X86_EFLAGS_CF); /* 0 or -1 */
}
int detect_memory(void)
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