v4.19.13 snapshot.
diff --git a/arch/x86/boot/edd.c b/arch/x86/boot/edd.c
new file mode 100644
index 0000000..223e425
--- /dev/null
+++ b/arch/x86/boot/edd.c
@@ -0,0 +1,182 @@
+/* -*- linux-c -*- ------------------------------------------------------- *
+ *
+ * Copyright (C) 1991, 1992 Linus Torvalds
+ * Copyright 2007 rPath, Inc. - All Rights Reserved
+ * Copyright 2009 Intel Corporation; author H. Peter Anvin
+ *
+ * This file is part of the Linux kernel, and is made available under
+ * the terms of the GNU General Public License version 2.
+ *
+ * ----------------------------------------------------------------------- */
+
+/*
+ * Get EDD BIOS disk information
+ */
+
+#include "boot.h"
+#include <linux/edd.h>
+#include "string.h"
+
+#if defined(CONFIG_EDD) || defined(CONFIG_EDD_MODULE)
+
+/*
+ * Read the MBR (first sector) from a specific device.
+ */
+static int read_mbr(u8 devno, void *buf)
+{
+ struct biosregs ireg, oreg;
+
+ initregs(&ireg);
+ ireg.ax = 0x0201; /* Legacy Read, one sector */
+ ireg.cx = 0x0001; /* Sector 0-0-1 */
+ ireg.dl = devno;
+ ireg.bx = (size_t)buf;
+
+ intcall(0x13, &ireg, &oreg);
+
+ return -(oreg.eflags & X86_EFLAGS_CF); /* 0 or -1 */
+}
+
+static u32 read_mbr_sig(u8 devno, struct edd_info *ei, u32 *mbrsig)
+{
+ int sector_size;
+ char *mbrbuf_ptr, *mbrbuf_end;
+ u32 buf_base, mbr_base;
+ extern char _end[];
+ u16 mbr_magic;
+
+ sector_size = ei->params.bytes_per_sector;
+ if (!sector_size)
+ sector_size = 512; /* Best available guess */
+
+ /* Produce a naturally aligned buffer on the heap */
+ buf_base = (ds() << 4) + (u32)&_end;
+ mbr_base = (buf_base+sector_size-1) & ~(sector_size-1);
+ mbrbuf_ptr = _end + (mbr_base-buf_base);
+ mbrbuf_end = mbrbuf_ptr + sector_size;
+
+ /* Make sure we actually have space on the heap... */
+ if (!(boot_params.hdr.loadflags & CAN_USE_HEAP))
+ return -1;
+ if (mbrbuf_end > (char *)(size_t)boot_params.hdr.heap_end_ptr)
+ return -1;
+
+ memset(mbrbuf_ptr, 0, sector_size);
+ if (read_mbr(devno, mbrbuf_ptr))
+ return -1;
+
+ *mbrsig = *(u32 *)&mbrbuf_ptr[EDD_MBR_SIG_OFFSET];
+ mbr_magic = *(u16 *)&mbrbuf_ptr[510];
+
+ /* check for valid MBR magic */
+ return mbr_magic == 0xAA55 ? 0 : -1;
+}
+
+static int get_edd_info(u8 devno, struct edd_info *ei)
+{
+ struct biosregs ireg, oreg;
+
+ memset(ei, 0, sizeof *ei);
+
+ /* Check Extensions Present */
+
+ initregs(&ireg);
+ ireg.ah = 0x41;
+ ireg.bx = EDDMAGIC1;
+ ireg.dl = devno;
+ intcall(0x13, &ireg, &oreg);
+
+ if (oreg.eflags & X86_EFLAGS_CF)
+ return -1; /* No extended information */
+
+ if (oreg.bx != EDDMAGIC2)
+ return -1;
+
+ ei->device = devno;
+ ei->version = oreg.ah; /* EDD version number */
+ ei->interface_support = oreg.cx; /* EDD functionality subsets */
+
+ /* Extended Get Device Parameters */
+
+ ei->params.length = sizeof(ei->params);
+ ireg.ah = 0x48;
+ ireg.si = (size_t)&ei->params;
+ intcall(0x13, &ireg, &oreg);
+
+ /* Get legacy CHS parameters */
+
+ /* Ralf Brown recommends setting ES:DI to 0:0 */
+ ireg.ah = 0x08;
+ ireg.es = 0;
+ intcall(0x13, &ireg, &oreg);
+
+ if (!(oreg.eflags & X86_EFLAGS_CF)) {
+ ei->legacy_max_cylinder = oreg.ch + ((oreg.cl & 0xc0) << 2);
+ ei->legacy_max_head = oreg.dh;
+ ei->legacy_sectors_per_track = oreg.cl & 0x3f;
+ }
+
+ return 0;
+}
+
+void query_edd(void)
+{
+ char eddarg[8];
+ int do_mbr = 1;
+#ifdef CONFIG_EDD_OFF
+ int do_edd = 0;
+#else
+ int do_edd = 1;
+#endif
+ int be_quiet;
+ int devno;
+ struct edd_info ei, *edp;
+ u32 *mbrptr;
+
+ if (cmdline_find_option("edd", eddarg, sizeof eddarg) > 0) {
+ if (!strcmp(eddarg, "skipmbr") || !strcmp(eddarg, "skip")) {
+ do_edd = 1;
+ do_mbr = 0;
+ }
+ else if (!strcmp(eddarg, "off"))
+ do_edd = 0;
+ else if (!strcmp(eddarg, "on"))
+ do_edd = 1;
+ }
+
+ be_quiet = cmdline_find_option_bool("quiet");
+
+ edp = boot_params.eddbuf;
+ mbrptr = boot_params.edd_mbr_sig_buffer;
+
+ if (!do_edd)
+ return;
+
+ /* Bugs in OnBoard or AddOnCards Bios may hang the EDD probe,
+ * so give a hint if this happens.
+ */
+
+ if (!be_quiet)
+ printf("Probing EDD (edd=off to disable)... ");
+
+ for (devno = 0x80; devno < 0x80+EDD_MBR_SIG_MAX; devno++) {
+ /*
+ * Scan the BIOS-supported hard disks and query EDD
+ * information...
+ */
+ if (!get_edd_info(devno, &ei)
+ && boot_params.eddbuf_entries < EDDMAXNR) {
+ memcpy(edp, &ei, sizeof ei);
+ edp++;
+ boot_params.eddbuf_entries++;
+ }
+
+ if (do_mbr && !read_mbr_sig(devno, &ei, mbrptr++))
+ boot_params.edd_mbr_sig_buf_entries = devno-0x80+1;
+ }
+
+ if (!be_quiet)
+ printf("ok\n");
+}
+
+#endif