summaryrefslogtreecommitdiff
path: root/client/bin/kernel.py
blob: fca8f7ef90e3833eca12e7d36b7eb68a0ed0a972 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
__author__ = """Copyright Martin J. Bligh, 2006"""

import os, shutil, copy, pickle, re, glob, time
from autotest_lib.client.bin.fd_stack import tee_output_logdir_mark
from autotest_lib.client.bin import kernel_config, os_dep, kernelexpand, test
from autotest_lib.client.bin import autotest_utils
from autotest_lib.client.common_lib import logging, utils


class kernel:
	""" Class for compiling kernels. 

	Data for the object includes the src files
	used to create the kernel, patches applied, config (base + changes),
	the build directory itself, and logged output

	Properties:
		job
			Backpointer to the job object we're part of
		autodir
			Path to the top level autotest dir (/usr/local/autotest)
		src_dir
			<tmp_dir>/src/
		build_dir
			<tmp_dir>/linux/
		config_dir
			<results_dir>/config/
		log_dir
			<results_dir>/debug/
		results_dir
			<results_dir>/results/
	"""

	autodir = ''

	def __init__(self, job, base_tree, subdir, tmp_dir, build_dir, leave = False):
		"""Initialize the kernel build environment

		job
			which job this build is part of
		base_tree
			base kernel tree. Can be one of the following:
				1. A local tarball
				2. A URL to a tarball
				3. A local directory (will symlink it)
				4. A shorthand expandable (eg '2.6.11-git3')
		subdir
			subdir in the results directory (eg "build")
			(holds config/, debug/, results/)
		tmp_dir

		leave
			Boolean, whether to leave existing tmpdir or not
		"""
		self.job = job
		self.autodir = job.autodir

		self.src_dir    = os.path.join(tmp_dir, 'src')
		self.build_dir  = os.path.join(tmp_dir, build_dir)
			# created by get_kernel_tree
		self.config_dir = os.path.join(subdir, 'config')
		self.log_dir    = os.path.join(subdir, 'debug')
		self.results_dir = os.path.join(subdir, 'results')
		self.subdir	= os.path.basename(subdir)

		self.installed_as = None

		if not leave:
			if os.path.isdir(self.src_dir):
				utils.system('rm -rf ' + self.src_dir)
			if os.path.isdir(self.build_dir):
				utils.system('rm -rf ' + self.build_dir)

		if not os.path.exists(self.src_dir):
			os.mkdir(self.src_dir)
		for path in [self.config_dir, self.log_dir, self.results_dir]:
			if os.path.exists(path):
				utils.system('rm -rf ' + path)
			os.mkdir(path)

		logpath = os.path.join(self.log_dir, 'build_log')
		self.logfile = open(logpath, 'w+')
		self.applied_patches = []

		self.target_arch = None
		self.build_target = 'bzImage'
		self.build_image = None

		arch = autotest_utils.get_current_kernel_arch()
		if arch == 's390' or arch == 's390x':
			self.build_target = 'image'
		elif arch == 'ia64':
			self.build_target = 'all'
			self.build_image = 'vmlinux.gz'

		if leave:
			return

		self.logfile.write('BASE: %s\n' % base_tree)

		# Where we have direct version hint record that
		# for later configuration selection.
		shorthand = re.compile(r'^\d+\.\d+\.\d+')
		if shorthand.match(base_tree):
			self.base_tree_version = base_tree
		else:
			self.base_tree_version = None
			
		# Actually extract the tree.  Make sure we know it occured
		self.extract(base_tree)


	def kernelexpand(self, kernel):
		# If we have something like a path, just use it as it is
		if '/' in kernel:
			return [kernel]

		# Find the configured mirror list.
		mirrors = self.job.config_get('mirror.mirrors')
		if not mirrors:
			# LEGACY: convert the kernel.org mirror
			mirror = self.job.config_get('mirror.ftp_kernel_org')
			if mirror:
				korg = 'http://www.kernel.org/pub/linux/kernel'
				mirrors = [
				  [ korg + '/v2.6', mirror + '/v2.6' ],
				  [ korg + '/people/akpm/patches/2.6',
				    mirror + '/akpm' ],
				  [ korg + '/people/mbligh',
				    mirror + '/mbligh' ],
				]

		patches = kernelexpand.expand_classic(kernel, mirrors)
		print patches

		return patches


	@logging.record
	@tee_output_logdir_mark
	def extract(self, base_tree):
		if os.path.exists(base_tree):
			self.get_kernel_tree(base_tree)
		else:
			base_components = self.kernelexpand(base_tree)
			print 'kernelexpand: '
			print base_components
			self.get_kernel_tree(base_components.pop(0))
			if base_components:      # apply remaining patches
				self.patch(*base_components)


	@logging.record
	@tee_output_logdir_mark
	def patch(self, *patches):
		"""Apply a list of patches (in order)"""
		if not patches:
			return
		print 'Applying patches: ', patches
		self.apply_patches(self.get_patches(patches))


	@logging.record
	@tee_output_logdir_mark
	def config(self, config_file = '', config_list = None, defconfig = False):
		self.set_cross_cc()
		config = kernel_config.kernel_config(self.job, self.build_dir,
			 self.config_dir, config_file, config_list,
			 defconfig, self.base_tree_version)


	def get_patches(self, patches):
		"""fetch the patches to the local src_dir"""
		local_patches = []
		for patch in patches:
			dest = os.path.join(self.src_dir, basename(patch))
			# FIXME: this isn't unique. Append something to it
			# like wget does if it's not there?
			print "get_file %s %s %s %s" % (patch, dest, self.src_dir, basename(patch))
			utils.get_file(patch, dest)
			# probably safer to use the command, not python library
			md5sum = utils.system_output('md5sum ' + dest).split()[0]
			local_patches.append((patch, dest, md5sum))
		return local_patches


	def apply_patches(self, local_patches):
		"""apply the list of patches, in order"""
		builddir = self.build_dir
		os.chdir(builddir)

		if not local_patches:
			return None
		for (spec, local, md5sum) in local_patches:
			if local.endswith('.bz2') or local.endswith('.gz'):
				ref = spec
			else:
				ref = force_copy(local, self.results_dir)
				ref = self.job.relative_path(ref)
			patch_id = "%s %s %s" % (spec, ref, md5sum)
			log = "PATCH: " + patch_id + "\n"
			print log
			cat_file_to_cmd(local, 'patch -p1 > /dev/null')
			self.logfile.write(log)
			self.applied_patches.append(patch_id)


	def get_kernel_tree(self, base_tree):
		"""Extract/link base_tree to self.build_dir"""
  
		# if base_tree is a dir, assume uncompressed kernel
		if os.path.isdir(base_tree):
			print 'Symlinking existing kernel source'
			os.symlink(base_tree, self.build_dir)

		# otherwise, extract tarball
		else:
			os.chdir(os.path.dirname(self.src_dir))
			# Figure out local destination for tarball
			tarball = os.path.join(self.src_dir, os.path.basename(base_tree))
			utils.get_file(base_tree, tarball)
			print 'Extracting kernel tarball:', tarball, '...'
			autotest_utils.extract_tarball_to_dir(tarball,
			                                      self.build_dir)


	def extraversion(self, tag, append=1):
		os.chdir(self.build_dir)
		extraversion_sub = r's/^EXTRAVERSION =\s*\(.*\)/EXTRAVERSION = '
		if append:
			p = extraversion_sub + '\\1-%s/' % tag
		else:
			p = extraversion_sub + '-%s/' % tag
		utils.system('mv Makefile Makefile.old')
		utils.system('sed "%s" < Makefile.old > Makefile' % p)


	@logging.record
	@tee_output_logdir_mark
	def build(self, make_opts = '', logfile = '', extraversion='autotest'):
		"""build the kernel

		make_opts
			additional options to make, if any
		"""
		os_dep.commands('gcc', 'make')
		if logfile == '':
			logfile = os.path.join(self.log_dir, 'kernel_build')
		os.chdir(self.build_dir)
		if extraversion:
			self.extraversion(extraversion)
		self.set_cross_cc()
		# setup_config_file(config_file, config_overrides)

		# Not needed on 2.6, but hard to tell -- handle failure
		utils.system('make dep', ignore_status=True)
		threads = 2 * autotest_utils.count_cpus()
		build_string = 'make -j %d %s %s' % (threads, make_opts,
					     self.build_target)
					# eg make bzImage, or make zImage
		print build_string
		system(build_string)
		if kernel_config.modules_needed('.config'):
			utils.system('make -j %d modules' % (threads))

		kernel_version = self.get_kernel_build_ver()
		kernel_version = re.sub('-autotest', '', kernel_version)
		self.logfile.write('BUILD VERSION: %s\n' % kernel_version)

		force_copy(self.build_dir+'/System.map', self.results_dir)


	def build_timed(self, threads, timefile = '/dev/null', make_opts = '',
							output = '/dev/null'):
		"""time the bulding of the kernel"""
		os.chdir(self.build_dir)
		self.set_cross_cc()

		self.clean(logged=False)
		build_string = "/usr/bin/time -o %s make %s -j %s vmlinux" \
			 			% (timefile, make_opts, threads)
		build_string += ' > %s 2>&1' % output
		print build_string
		utils.system(build_string)

		if (not os.path.isfile('vmlinux')):
			errmsg = "no vmlinux found, kernel build failed"
			raise error.TestError(errmsg)


	@logging.record
	@tee_output_logdir_mark
	def clean(self):
		"""make clean in the kernel tree"""
		os.chdir(self.build_dir) 
		print "make clean"
		utils.system('make clean > /dev/null 2> /dev/null')


	@logging.record
	@tee_output_logdir_mark
	def mkinitrd(self, version, image, system_map, initrd):
		"""Build kernel initrd image.
		Try to use distro specific way to build initrd image.
		Parameters:
			version
				new kernel version
			image
				new kernel image file
			system_map
				System.map file
			initrd
				initrd image file to build
		"""
		vendor = autotest_utils.get_os_vendor()
		
		if os.path.isfile(initrd):
			print "Existing %s file, will remove it." % initrd
			os.remove(initrd)

		args = self.job.config_get('kernel.mkinitrd_extra_args')

		# don't leak 'None' into mkinitrd command
		if not args:
			args = ''

		if vendor in ['Red Hat', 'Fedora Core']:
			utils.system('mkinitrd %s %s %s' % (args, initrd, version))
		elif vendor in ['SUSE']:
			utils.system('mkinitrd %s -k %s -i %s -M %s' % (args, image, initrd, system_map))
		elif vendor in ['Debian', 'Ubuntu']:
			if os.path.isfile('/usr/sbin/mkinitrd'):
				cmd = '/usr/sbin/mkinitrd'
			elif os.path.isfile('/usr/sbin/mkinitramfs'):
				cmd = '/usr/sbin/mkinitramfs'
			else:
				raise error.TestError('No Debian initrd builder')
			utils.system('%s %s -o %s %s' % (cmd, args, initrd, version))
		else:
			raise error.TestError('Unsupported vendor %s' % vendor)


	def set_build_image(self, image):
		self.build_image = image


	@logging.record
	@tee_output_logdir_mark
	def install(self, tag='autotest', prefix = '/'):
		"""make install in the kernel tree"""

		# Record that we have installed the kernel, and
		# the tag under which we installed it.
		self.installed_as = tag

		os.chdir(self.build_dir)

		if not os.path.isdir(prefix):
			os.mkdir(prefix)
		self.boot_dir = os.path.join(prefix, 'boot')
		if not os.path.isdir(self.boot_dir):
			os.mkdir(self.boot_dir)

		if not self.build_image:
			images = glob.glob('arch/*/boot/' + self.build_target)
			if len(images):
				self.build_image = images[0]
			else:
				self.build_image = self.build_target

		# remember installed files
		self.vmlinux = self.boot_dir + '/vmlinux-' + tag
		if (self.build_image != 'vmlinux'):
			self.image = self.boot_dir + '/vmlinuz-' + tag
		else:
			self.image = self.vmlinux
		self.system_map = self.boot_dir + '/System.map-' + tag
		self.config = self.boot_dir + '/config-' + tag
		self.initrd = ''

		# copy to boot dir
		autotest_utils.force_copy('vmlinux', self.vmlinux)
		if (self.build_image != 'vmlinux'):
			force_copy(self.build_image, self.image)
		autotest_utils.force_copy('System.map', self.system_map)
		autotest_utils.force_copy('.config', self.config)

		if not kernel_config.modules_needed('.config'):
			return

		utils.system('make modules_install INSTALL_MOD_PATH=%s' % prefix)
		if prefix == '/':
			self.initrd = self.boot_dir + '/initrd-' + tag
			self.mkinitrd(self.get_kernel_build_ver(), self.image,
				      self.system_map, self.initrd)


	def add_to_bootloader(self, tag='autotest', args=''):
		""" add this kernel to bootloader, taking an
		    optional parameter of space separated parameters
		    e.g.:  kernel.add_to_bootloader('mykernel', 'ro acpi=off')
		"""

		# remove existing entry if present
		self.job.bootloader.remove_kernel(tag)

		# pull the base argument set from the job config,
		baseargs = self.job.config_get('boot.default_args')
		if baseargs:
			args = baseargs + " " + args
		
		# otherwise populate from /proc/cmdline
		# if not baseargs:
		#	baseargs = open('/proc/cmdline', 'r').readline().strip()
		# NOTE: This is unnecessary, because boottool does it.

		root = None
		roots = [x for x in args.split() if x.startswith('root=')]
		if roots:
			root = re.sub('^root=', '', roots[0])
		arglist = [x for x in args.split() if not x.startswith('root=')]
		args = ' '.join(arglist)

		# add the kernel entry
		# add_kernel(image, title='autotest', initrd='')
		self.job.bootloader.add_kernel(self.image, tag, self.initrd, \
						args = args, root = root)


	def get_kernel_build_arch(self, arch=None):
		"""
		Work out the current kernel architecture (as a kernel arch)
		"""
		if not arch:
			arch = autotest_utils.get_current_kernel_arch()
		if re.match('i.86', arch):
			return 'i386'
		elif re.match('sun4u', arch):
			return 'sparc64'
		elif re.match('arm.*', arch):
			return 'arm'
		elif re.match('sa110', arch):
			return 'arm'
		elif re.match('s390x', arch):
			return 's390'
		elif re.match('parisc64', arch):
			return 'parisc'
		elif re.match('ppc.*', arch):
			return 'powerpc'
		elif re.match('mips.*', arch):
			return 'mips'
		else:
			return arch


	def get_kernel_build_release(self):
		releasem = re.compile(r'.*UTS_RELEASE\s+"([^"]+)".*');
		versionm = re.compile(r'.*UTS_VERSION\s+"([^"]+)".*');

		release = None
		version = None

		for file in [ self.build_dir + "/include/linux/version.h",
			      self.build_dir + "/include/linux/utsrelease.h",
			      self.build_dir + "/include/linux/compile.h" ]:
			if os.path.exists(file):
				fd = open(file, 'r')
				for line in fd.readlines():
					m = releasem.match(line)
					if m:
						release = m.groups()[0]
					m = versionm.match(line)
					if m:
						version = m.groups()[0]
				fd.close()

		return (release, version)

	
	def get_kernel_build_ident(self):
		(release, version) = self.get_kernel_build_release()

		if not release or not version:
			raise error.JobError('kernel has no identity')

		return release + '::' + version


	def boot(self, args='', ident=1):
		""" install and boot this kernel, do not care how
		    just make it happen.
		"""

		# If we can check the kernel identity do so.
		if ident:
			when = int(time.time())
			ident = self.get_kernel_build_ident()
			args += " IDENT=%d" % (when)

			self.job.next_step_prepend(["job.kernel_check_ident",
						    when, ident, self.subdir,
						    self.applied_patches])

		# Check if the kernel has been installed, if not install
		# as the default tag and boot that.
		if not self.installed_as:
			self.install()

		# Boot the selected tag.
		self.add_to_bootloader(args=args, tag=self.installed_as)

		# Boot it.
		self.job.reboot(tag=self.installed_as)


	def get_kernel_build_ver(self):
		"""Check Makefile and .config to return kernel version"""
		version = patchlevel = sublevel = extraversion = localversion = ''

		for line in open(self.build_dir + '/Makefile', 'r').readlines():
			if line.startswith('VERSION'):
				version = line[line.index('=') + 1:].strip()
			if line.startswith('PATCHLEVEL'):
				patchlevel = line[line.index('=') + 1:].strip()
			if line.startswith('SUBLEVEL'):
				sublevel = line[line.index('=') + 1:].strip()
			if line.startswith('EXTRAVERSION'):
				extraversion = line[line.index('=') + 1:].strip()

		for line in open(self.build_dir + '/.config', 'r').readlines():
			if line.startswith('CONFIG_LOCALVERSION='):
				localversion = line.rstrip().split('"')[1]

		return "%s.%s.%s%s%s" %(version, patchlevel, sublevel, extraversion, localversion)


	def set_build_target(self, build_target):
		if build_target:
			self.build_target = build_target
			print 'BUILD TARGET: %s' % self.build_target


	def set_cross_cc(self, target_arch=None, cross_compile=None,
			 build_target='bzImage'):
		"""Set up to cross-compile.
			This is broken. We need to work out what the default
			compile produces, and if not, THEN set the cross
			compiler.
		"""

		if self.target_arch:
			return

		# if someone has set build_target, don't clobber in set_cross_cc
		# run set_build_target before calling set_cross_cc
		if not self.build_target:
			self.set_build_target(build_target)

		# If no 'target_arch' given assume native compilation
		if target_arch == None:
			target_arch = autotest_utils.get_current_kernel_arch()
			if target_arch == 'ppc64':
				if self.build_target == 'bzImage':
					self.build_target = 'vmlinux'

		if not cross_compile:
			cross_compile = self.job.config_get('kernel.cross_cc')

		if cross_compile:
			os.environ['CROSS_COMPILE'] = cross_compile
		else:
			if os.environ.has_key('CROSS_COMPILE'):
				del os.environ['CROSS_COMPILE']
	
		return                 # HACK. Crap out for now.

		# At this point I know what arch I *want* to build for
		# but have no way of working out what arch the default
		# compiler DOES build for.

		# Oh, and BTW, install_package() doesn't exist yet.

		if target_arch == 'ppc64':
			install_package('ppc64-cross')
			cross_compile = os.path.join(self.autodir, 'sources/ppc64-cross/bin')

		elif target_arch == 'x86_64':
			install_package('x86_64-cross')
			cross_compile = os.path.join(self.autodir, 'sources/x86_64-cross/bin')

		os.environ['ARCH'] = self.target_arch = target_arch

		self.cross_compile = cross_compile
		if self.cross_compile:
			os.environ['CROSS_COMPILE'] = self.cross_compile


	def pickle_dump(self, filename):
		"""dump a pickle of ourself out to the specified filename

		we can't pickle the backreference to job (it contains fd's), 
		nor would we want to. Same for logfile (fd's).
		"""
		temp = copy.copy(self)
		temp.job = None
		temp.logfile = None
		pickle.dump(temp, open(filename, 'w'))


class rpm_kernel:
	""" Class for installing rpm kernel package
	"""

	def __init__(self, job, rpm_package, subdir):
		self.job = job
		self.rpm_package = rpm_package
		self.log_dir = os.path.join(subdir, 'debug')
		self.subdir = os.path.basename(subdir)
		if os.path.exists(self.log_dir):
			utils.system('rm -rf ' + self.log_dir)
		os.mkdir(self.log_dir)
		self.installed_as = None


	@logging.record
	@tee_output_logdir_mark
	def install(self, tag='autotest'):
		self.installed_as = tag

		self.rpm_name = utils.system_output('rpm -qp ' + self.rpm_package)

		# install
		utils.system('rpm -i --force ' + self.rpm_package)

		# get file list
		files = utils.system_output('rpm -ql ' + self.rpm_name).splitlines()

		# search for vmlinuz
		for file in files:
			if file.startswith('/boot/vmlinuz'):
				self.image = file
				break
		else:
			errmsg = "%s doesn't contain /boot/vmlinuz"
			errmsg %= self.rpm_package
			raise error.TestError(errmsg)

		# search for initrd
		self.initrd = ''
		for file in files:
			if file.startswith('/boot/initrd'):
				self.initrd = file
				break

		# get version and release number
		self.version, self.release = utils.system_output(
			'rpm --queryformat="%{VERSION}\\n%{RELEASE}\\n" -q ' + self.rpm_name).splitlines()[0:2]


	def add_to_bootloader(self, tag='autotest', args=''):
		""" Add this kernel to bootloader
		"""

		# remove existing entry if present
		self.job.bootloader.remove_kernel(tag)

		# pull the base argument set from the job config
		baseargs = self.job.config_get('boot.default_args')
		if baseargs:
			args = baseargs + ' ' + args

		# otherwise populate from /proc/cmdline
		# if not baseargs:
		#	baseargs = open('/proc/cmdline', 'r').readline().strip()
		# NOTE: This is unnecessary, because boottool does it.

		root = None
		roots = [x for x in args.split() if x.startswith('root=')]
		if roots:
			root = re.sub('^root=', '', roots[0])
		arglist = [x for x in args.split() if not x.startswith('root=')]
		args = ' '.join(arglist)

		# add the kernel entry
		self.job.bootloader.add_kernel(self.image, tag, self.initrd, args = args, root = root)


	def boot(self, args='', ident=1):
		""" install and boot this kernel
		"""

		# Check if the kernel has been installed, if not install
		# as the default tag and boot that.
		if not self.installed_as:
			self.install()

		# If we can check the kernel identity do so.
		if ident:
			when = int(time.time())
			ident = '-'.join([self.version,
					  self.rpm_name.split('-')[1],
					  self.release])
			args += " IDENT=%d" % (when)

		self.job.next_step_prepend(["job.kernel_check_ident",
			when, ident, self.subdir, 'rpm'])

		# Boot the selected tag.
		self.add_to_bootloader(args=args, tag=self.installed_as)

		# Boot it.
		self.job.reboot(tag=self.installed_as)


# pull in some optional site-specific path pre-processing
try:
	import site_kernel
	preprocess_path = site_kernel.preprocess_path
	del site_kernel
except ImportError:
	# just make the preprocessor a nop
	def preprocess_path(path):
		return path

def auto_kernel(job, path, subdir, tmp_dir, build_dir, leave=False):
	"""\
	Create a kernel object, dynamically selecting the appropriate class to use
	based on the path provided.
	"""
	path = preprocess_path(path)
	if path.endswith('.rpm'):
		return rpm_kernel(job, path, subdir)
	else:
		return kernel(job, path, subdir, tmp_dir, build_dir, leave)