From 3b0299dd657cff4c5a0a65a8970d4dab4c7b889b Mon Sep 17 00:00:00 2001
From: David van Moolenbroek <david@minix3.org>
Date: Mon, 22 Dec 2014 23:15:02 +0000
Subject: [PATCH] bootloader: pass memory map to kernel

Previously, the bootloader would only provide a single memory range.
At least on VirtualBox, this memory range includes the ACPI tables,
which the kernel then happily overwrites when executing VM.  Much of
the infrastructure to use a fullblown memory map is already in place;
this patch adds the last (and strangely missing) bit of generating
the memory map in a multiboot-compatible way.

It should be noted that both the bootloader and the kernel actually
violate the multiboot specification by not packing the structure for
the memory ranges.  This is a NetBSD bug, but it is also a nonissue
for (our) practical purposes.  It can be fixed without changing the
code added in this patch.

Change-Id: I7c0a307a8a8133239531e1d2b80f376849f90247
---
 sys/arch/i386/stand/lib/exec.c | 51 ++++++++++++++++++++++++++++++++++
 1 file changed, 51 insertions(+)

diff --git a/sys/arch/i386/stand/lib/exec.c b/sys/arch/i386/stand/lib/exec.c
index 3c0b94c4b..b555b8774 100644
--- a/sys/arch/i386/stand/lib/exec.c
+++ b/sys/arch/i386/stand/lib/exec.c
@@ -666,6 +666,49 @@ userconf_init(void)
 	}
 }
 
+#if defined(PASS_MEMMAP) && defined(__minix)
+/*
+ * Construct a memory map for the multiboot info structure, with memory ranges
+ * as reported by the BIOS.  If successful, set the HAS_MMAP flag.  Code copied
+ * largely from bootinfo_memmap.c.
+ */
+static void
+memmap_init(struct multiboot_info * mbi)
+{
+	multiboot_memory_map_t *mmap;
+	int buf[5], i, nranges;
+
+	nranges = 0;
+	i = 0;
+	do {
+		if (getmementry(&i, buf))
+			break;
+		nranges++;
+	} while (i);
+
+	if (nranges == 0)
+		return;
+
+	mbi->mmap_length = sizeof(multiboot_memory_map_t) * nranges;
+
+	mmap = alloc(mbi->mmap_length);
+
+	mbi->mmap_addr = vtophys(mmap);
+
+	i = 0;
+	while (nranges-- > 0) {
+		getmementry(&i, buf);
+
+		/* Stupid tricks to deal with alignment issues. */
+		memcpy(&mmap->mm_base_addr, buf, sizeof(buf));
+		mmap->mm_size = sizeof(*mmap) - sizeof(mmap->mm_size);
+		mmap++;
+	}
+
+	mbi->mi_flags |= MULTIBOOT_INFO_HAS_MMAP;
+}
+#endif /* PASS_MEMMAP && __minix */
+
 int
 exec_multiboot(const char *file, char *args)
 {
@@ -718,6 +761,14 @@ exec_multiboot(const char *file, char *args)
 		}
 	}
 
+#if defined(PASS_MEMMAP) && defined(__minix)
+	/*
+	 * The MINIX3 kernel needs a full memory map.  Without it, it will do
+	 * silly things such as overwriting the ACPI tables.
+	 */
+	memmap_init(mbi);
+#endif /* PASS_MEMMAP && __minix */
+
 #ifdef DEBUG
 	printf("Start @ 0x%lx [%ld=0x%lx-0x%lx]...\n", marks[MARK_ENTRY],
 	    marks[MARK_NSYM], marks[MARK_SYM], marks[MARK_END]);
-- 
2.44.0