I have a machine with both Linux and Windows installed on the hard
drive. Linux runs on the bare metal and I occasionally run the Windows
install in a VM using KVM pointed at /dev/sda. However if I'm not quick
enough, or Windows decides to reboot when I'm not around to notice, the
grub running under KVM will decide to boot Linux and much confusion
ensues.
I couldn't find an easy way to test what the running environment was, so
I knocked up a simple testpci command that allows me to test for the
existence of a PCI device and change the default boot option based on
that. I have:
| if testpci 8086:1237; then
| set default="2"
| fi
in my grub.cfg to correctly select the Windows partition if the qemu
provided host bridge is present.
Signed-off-by: Jonathan McDowell <nood...@earth.li>
-----
=== modified file 'grub-core/Makefile.core.def'
--- grub-core/Makefile.core.def 2012-09-08 07:40:24 +0000
+++ grub-core/Makefile.core.def 2012-09-27 21:00:31 +0000
@@ -837,6 +837,12 @@
};
module = {
+ name = testpci;
+ common = commands/testpci.c;
+ enable = pci;
+};
+
+module = {
name = true;
common = commands/true.c;
};
=== added file 'grub-core/commands/testpci.c'
--- grub-core/commands/testpci.c 1970-01-01 00:00:00 +0000
+++ grub-core/commands/testpci.c 2012-09-27 21:15:02 +0000
@@ -0,0 +1,75 @@
+/* testpci.c - Test for PCI device existence. */
+/*
+ * GRUB -- GRand Unified Bootloader
+ * Copyright (C) 2012 Free Software Foundation, Inc.
+ *
+ * GRUB 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 3 of the License, or
+ * (at your option) any later version.
+ *
+ * GRUB 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 GRUB. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <grub/pci.h>
+#include <grub/dl.h>
+#include <grub/extcmd.h>
+#include <grub/misc.h>
+#include <grub/i18n.h>
+
+GRUB_MOD_LICENSE ("GPLv3+");
+
+static int pcifound;
+static grub_pci_id_t pcisearch;
+
+static int NESTED_FUNC_ATTR
+grub_testpci_iter (grub_pci_device_t dev __attribute__ ((unused)),
+ grub_pci_id_t pciid)
+{
+ if (pciid == pcisearch) {
+ pcifound = 1;
+ return 1;
+ }
+
+ return 0;
+}
+
+static grub_err_t
+grub_cmd_testpci (grub_command_t ctxt __attribute__ ((unused)),
+ int argc,
+ char **args)
+{
+ pcifound = 0;
+
+ if (argc != 1)
+ return grub_error (GRUB_ERR_BAD_ARGUMENT, "Device to search for required");
+
+ if ((grub_strlen(args[0]) != 9) || args[0][4] != ':')
+ return grub_error (GRUB_ERR_BAD_ARGUMENT, "Device ID must be xxxx:yyyy");
+
+ pcisearch = grub_strtoul(args[0], 0, 16) +
+ (grub_strtoul(&args[0][5], 0, 16) << 16);
+
+ grub_pci_iterate (grub_testpci_iter);
+
+ return pcifound ? GRUB_ERR_NONE : grub_error (GRUB_ERR_TEST_FAILURE,
"false");
+}
+
+static grub_command_t cmd;
+
+GRUB_MOD_INIT(testpci)
+{
+ cmd = grub_register_command ("testpci", grub_cmd_testpci, "xxxx:yyyy",
+ N_("Test for PCI device existence."));
+}
+
+GRUB_MOD_FINI(testpci)
+{
+ grub_unregister_command (cmd);
+}
-----
J.
--
I'm out of bed and dressed. What more do you want?
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