Operating Systems 2018F: Tutorial 7 - Revision history

Housedhorse: /* Tasks/Questions */

2018-11-05T20:52:04Z

Tasks/Questions

← Older revision		Revision as of 20:52, 5 November 2018
Line 41:		Line 41:

	# What can you do with the Makefile other than type "make"?		# What can you do with the Makefile other than type "make"?
	# How much data can you write to /dev/remember? What determines the limit? (Hint: try writing remember.c to /dev/remember)		# How much data can you write to /dev/remember? What determines the limit? (Hint: try writing the contents of remember.c to /dev/remember)
	# When is data being allocated? When is it deallocated?		# When is data being allocated? When is it deallocated?
	# How can you increase the amount of data that /dev/remember stores? (Hint: what is saved_data_order for?)		# How can you increase the amount of data that /dev/remember stores? (Hint: what is saved_data_order for?)

2018-11-04T22:46:53Z

Tasks/Questions

← Older revision		Revision as of 22:46, 4 November 2018
Line 37:		Line 37:

	==Tasks/Questions==		==Tasks/Questions==

			A good resource is [https://learnlinuxconcepts.blogspot.com/2014/02/linux-memory-management.html this page] on Linux kernel memory management.

	# What can you do with the Makefile other than type "make"?		# What can you do with the Makefile other than type "make"?

2018-11-04T22:36:56Z

Tasks/Questions

← Older revision		Revision as of 22:36, 4 November 2018
Line 41:		Line 41:
	# How much data can you write to /dev/remember? What determines the limit? (Hint: try writing remember.c to /dev/remember)		# How much data can you write to /dev/remember? What determines the limit? (Hint: try writing remember.c to /dev/remember)
	# When is data being allocated? When is it deallocated?		# When is data being allocated? When is it deallocated?
	# How ~~could~~ you increase the amount of data that /dev/remember stores? (Hint: what is saved_data_order for?)		# How can you increase the amount of data that /dev/remember stores? (Hint: what is saved_data_order for?)
	# Does the kernel use virtual or physical addresses for its own data structures?		# Does the kernel use virtual or physical addresses for its own data structures?
	# How are we copying data to and from kernel space? Is it the same way we did before?		# How are we copying data to and from kernel space? Is it the same way we did before?

2018-11-04T16:04:03Z

Tasks/Questions

← Older revision		Revision as of 16:04, 4 November 2018
Line 43:		Line 43:
	# How could you increase the amount of data that /dev/remember stores? (Hint: what is saved_data_order for?)		# How could you increase the amount of data that /dev/remember stores? (Hint: what is saved_data_order for?)
	# Does the kernel use virtual or physical addresses for its own data structures?		# Does the kernel use virtual or physical addresses for its own data structures?
			# How are we copying data to and from kernel space? Is it the same way we did before?
	# What was changed from newgetpid.c that allows the /dev/remember device to be written to? What parts of the code had to be changed? What had to be added?		# What was changed from newgetpid.c that allows the /dev/remember device to be written to? What parts of the code had to be changed? What had to be added?

2018-11-04T16:01:39Z

← Older revision		Revision as of 16:01, 4 November 2018
Line 1:		Line 1:
	~~'''This tutorial is not yet finalized.'''~~

	Again in this tutorial you will be building and installing kernel modules. You will need root access to install kernel modules.		Again in this tutorial you will be building and installing kernel modules. You will need root access to install kernel modules.

2018-11-04T16:01:05Z

Makefile

← Older revision		Revision as of 16:01, 4 November 2018
Line 275:		Line 275:

	===Makefile===		===Makefile===

			Note that the large spaces below should be tabs.

	<source lang="make" line>		<source lang="make" line>

2018-11-04T16:00:48Z

Makefile

← Older revision		Revision as of 16:00, 4 November 2018
Line 282:		Line 282:
	PWD := $(shell pwd)		PWD := $(shell pwd)
	default:		default:
	$(MAKE) -C $(KDIR) SUBDIRS=$(PWD) modules		$(MAKE) -C $(KDIR) SUBDIRS=$(PWD) modules

	clean:		clean:
	/bin/rm -f .o .ko *~		/bin/rm -f .o .ko *~
	/bin/rm -f Module.symvers modules.order Modules.symvers *.mod.c		/bin/rm -f Module.symvers modules.order Modules.symvers *.mod.c
	/bin/rm -f .*o.cmd .cache.mk		/bin/rm -f .*o.cmd .cache.mk
	/bin/rm -rf .tmp_versions		/bin/rm -rf .tmp_versions

	zip:		zip:
	rm -f $(MODNAME).zip		rm -f $(MODNAME).zip
	mkdir $(MODNAME)		mkdir $(MODNAME)
	cp -a Makefile $(MODNAME).c $(MODNAME)		cp -a Makefile $(MODNAME).c $(MODNAME)
	zip -r $(MODNAME).zip $(MODNAME)		zip -r $(MODNAME).zip $(MODNAME)
	rm -rf $(MODNAME)		rm -rf $(MODNAME)
	</source>		</source>

2018-11-04T15:59:36Z

Tasks/Questions

← Older revision		Revision as of 15:59, 4 November 2018
Line 40:		Line 40:
	==Tasks/Questions==		==Tasks/Questions==

			# What can you do with the Makefile other than type "make"?
			# How much data can you write to /dev/remember? What determines the limit? (Hint: try writing remember.c to /dev/remember)
			# When is data being allocated? When is it deallocated?
			# How could you increase the amount of data that /dev/remember stores? (Hint: what is saved_data_order for?)
			# Does the kernel use virtual or physical addresses for its own data structures?
			# What was changed from newgetpid.c that allows the /dev/remember device to be written to? What parts of the code had to be changed? What had to be added?

	==Code==		==Code==

2018-11-04T15:51:26Z

remember.c

← Older revision		Revision as of 15:51, 4 November 2018
Line 222:		Line 222:
	}		}

	remember_class->devnode = remember_devnode;		remember_class->devnode = remember_devnode;

	remember_device = device_create(remember_class, NULL,		remember_device = device_create(remember_class, NULL,

2018-11-04T15:50:24Z

Getting started

← Older revision		Revision as of 15:50, 4 November 2018
Line 9:		Line 9:
	==Getting started==		==Getting started==

			First, make sure your system is ready to build things. On ubuntu:

			sudo apt install build-essential libelf-dev
			sudo apt clean

			Note that libelf-dev is a new addition. (To update your system, run "sudo apt update; sudo apt dist-upgrade")

			Download and unzip [https://homeostasis.scs.carleton.ca/~soma/os-2018f/code/tut7/remember.zip remember.zip]. From the command line:

			wget https://homeostasis.scs.carleton.ca/~soma/os-2018f/code/tut7/remember.zip
			unzip remember.zip

			Next, build the module and install it:

			cd remember
			make
			sudo insmod remember.ko

			And then test the module:

			echo "Hello world" > /dev/remember
			cat /dev/remember

			Be sure to check the kernel logs before and after. You may even want to follow the logs as you play with the module. To do this, run:

			tail -f /var/log/kern.log

			You'll want to do this in a separate window.

	==Tasks/Questions==		==Tasks/Questions==