[PATCH]kdump: pass noefi and acpi_rsdp= to 2nd kernel

[Dave Young]

In case efi booting, kdump need kernel parameter noefi and acpi_rsdp=
to disable efi reinit and retrieve the acpi root table physical address.

Add a function cmdline_add_efi to get the address from /sys/firmware/efi/systab
If there's no such file or read fail the function will just do nothing.

Tested efi boot Fedora 17 on thinkpad T420.

Signed-off-by: Dave Young <dyoung at redhat.com>
---
 kexec/arch/i386/crashdump-x86.c |   47 ++++++++++++++++++++++++++++++++++++++++
 1 file changed, 47 insertions(+)

--- kexec-tools.orig/kexec/arch/i386/crashdump-x86.c
+++ kexec-tools/kexec/arch/i386/crashdump-x86.c
@@ -27,6 +27,7 @@
 #include <sys/types.h>
 #include <sys/stat.h>
 #include <unistd.h>
+#include <fcntl.h>
 #include "../../kexec.h"
 #include "../../kexec-elf.h"
 #include "../../kexec-syscall.h"
@@ -658,6 +659,51 @@ static int cmdline_add_memmap_acpi(char 
 	return 0;
 }
 
+/* Appends 'noefi acpi_rsdp=' commandline for efi boot crash dump */
+static void cmdline_add_efi(char *cmdline)
+{
+	int cmdlen, len, fd, ret, i = 0;
+	char str_efi[64], str_tmp[32];
+
+	memset(str_efi, 0x0, sizeof(str_efi));
+	memset(str_tmp, 0x0, sizeof(str_tmp));
+	snprintf(str_efi, 18, "%s", " noefi acpi_rsdp=");
+
+	fd = open("/sys/firmware/efi/systab", O_RDONLY);
+	if (fd < 0)
+		return;
+
+	while(1) {
+		ret = read(fd, &str_tmp[i], 1);
+		if (ret <= 0)
+			goto out_close;
+		if (str_tmp[i] == '\n') {
+			str_tmp[i] = '\0';
+			break;
+		}
+		i++;
+	}
+
+	if (!(strncmp(str_tmp, "ACPI20=", 7)))
+		strcat(str_efi, &str_tmp[7]);
+	else if (!(strncmp(str_tmp, "ACPI=", 5)))
+		strcat(str_efi, &str_tmp[5]);
+	else
+		goto out_close;
+
+	len = strlen(str_efi);
+	cmdlen = strlen(cmdline) + len;
+	if (cmdlen > (COMMAND_LINE_SIZE - 1))
+		die("Command line overflow\n");
+	strcat(cmdline, str_efi);
+
+	dbgprintf("Command line after adding efi\n");
+	dbgprintf("%s\n", cmdline);
+
+out_close:
+	close(fd);
+}
+
 static void get_backup_area(unsigned long *start, unsigned long *end)
 {
 	const char *iomem = proc_iomem();
@@ -830,6 +876,7 @@ int load_crashdump_segments(struct kexec
 	if (delete_memmap(memmap_p, elfcorehdr, memsz) < 0)
 		return -1;
 	cmdline_add_memmap(mod_cmdline, memmap_p);
+	cmdline_add_efi(mod_cmdline);
 	cmdline_add_elfcorehdr(mod_cmdline, elfcorehdr);
 
 	/* Inform second kernel about the presence of ACPI tables. */