1 files changed, 73 insertions, 0 deletions
diff --git a/arch/x86/lib/memory16.S b/arch/x86/lib/memory16.S
new file mode 100644
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+++ b/arch/x86/lib/memory16.S
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+/*
+ * Copyright (C) 2009 Juergen Beisert, Pengutronix
+ *
+ * This code was inspired by the GRUB2 project.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of
+ * the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston,
+ * MA 02111-1307 USA
+ *
+ */
+
+/**
+ * @file
+ * @brief Query the memory layout information from the BIOS
+ *
+ * Note: This function is running in flat and real mode. Due to some
+ * other restrictions it must running from an address space below 0x10000
+ */
+
+/**
+ * @fn unsigned short bios_get_memsize(void)
+ * @brief Does a BIOS call "INT 15H, AH=88H" to get extended memory size
+ * @return Extended memory size in KB
+ *
+ * @note This call is limited to 64 MiB. So, if the system provides more than
+ * 64 MiB of memory, still 64 MiB are reported.
+ *
+ */
+
+#ifndef DOXYGEN_SHOULD_SKIP_THIS
+
+	.section .boot.text.bios_get_memsize, "ax"
+	.code32
+	.globl bios_get_memsize
+	.type bios_get_memsize, @function
+
+	.extern prot_to_real
+
+bios_get_memsize:
+
+	pushl %ebp
+
+	call prot_to_real	/* enter real mode */
+	.code16
+
+	movb $0x88, %ah
+	int $0x15
+
+	movw %ax, %dx
+
+	DATA32	call real_to_prot
+
+	.code32
+
+	movw %dx, %ax
+
+	popl %ebp
+	ret
+
+	.size bios_get_memsize, .-bios_get_memsize
+
+#endif