Support "extended attributes" for INT 15h, AX=E820h

Some blithering idiot thought it was a good idea to introduce
"extended attributes" for INT 15h, AX=E820h, and in doing so, breaking
compatibility with ALL E820 users out there.  F*cking morons.
Implement handling of extended attributes in:

- e820 parsing in the core
- e820 parsing in libcom32
- e820 parsing *and proxying* in memdisk

The latter is the really painful one.

Signed-off-by: H. Peter Anvin <hpa@zytor.com>

1 files changed, 8 insertions, 1 deletions

diff --git a/com32/lib/syslinux/memmap.c b/com32/lib/syslinux/memmap.c
index 5a0a34f7..c5f1b251 100644
--- a/com32/lib/syslinux/memmap.c
+++ b/com32/lib/syslinux/memmap.c
@@ -46,6 +46,7 @@ struct e820_entry {
   uint64_t start;
   uint64_t len;
   uint32_t type;
+  uint32_t extattr;
 };
 
 struct syslinux_memmap *syslinux_memory_map(void)
@@ -74,7 +75,7 @@ struct syslinux_memmap *syslinux_memory_map(void)
   ireg.eax.l    = 0xe820;
   ireg.edx.l    = 0x534d4150;
   ireg.ebx.l    = 0;
-  ireg.ecx.l    = 20;
+  ireg.ecx.l    = sizeof(*e820buf);
   ireg.es       = SEG(e820buf);
   ireg.edi.w[0] = OFFS(e820buf);
 
@@ -86,6 +87,12 @@ struct syslinux_memmap *syslinux_memory_map(void)
 	(oreg.ecx.l < 20))
       break;
 
+    if (oreg.ecx.l >= 24)
+      e820buf->extattr = 1;	/* Enabled, normal */
+
+    if (!(e820buf->extattr & 1))
+      continue;
+
     type = e820buf->type == 1 ? SMT_FREE : SMT_RESERVED;
     start = e820buf->start;
     len = e820buf->len;