Annotation of wikisrc/netbsd_kernel_development_setup.mdwn, revision 1.2
1.1 wiki 1: # Introduction
2: This HOWTO is meant to be a manual for easy setup for kernel development/test environment which can be used by students
3: during Google Summer of Code.
4:
5: The most convenient way how to develop and test operating system is do it in virtual machine one of the most known/used emulators is a QEMU.
6:
7:
8: ## System Build/Installation
9:
10: We always can setup our environment in two ways First I would like to describe automatic way where user can use wonderful application anita which can do unattended NetBSD installations. Later we will show how to do this installation manually.
11:
12: ### Automatic Environemnt Setup
13:
14: #### Prerequsities
15:
16: You need the follwoing prerequisites from pkgsrc:
17:
18: * emulators/qemu >= 0.15.1nb5
19: * misc/py-anita
20:
21: #### System build/instalaltion
22:
23: Build a full -current/i386 release with debug symbols using build.sh.
1.2 ! wiki 24: Use something like "build.sh -V COPTS=-g release"; you
1.1 wiki 25: will probably also need other options to set directories,
26: architectures, etc, but those are outside the scope of this document.
1.2 ! wiki 27: Do not specify "-V MKDEBUG=YES", because as of 2013-01-17,
! 28: that puts the debug symbols in a separate debug.tgz file set which
! 29: sysinst is currently unable to install.
1.1 wiki 30:
31: Debug builds sometimes fail with error messages indicating that
32: shared libraries are missing or corrupted. This is PR 44046.
33: If this happens to you, retry to build, or better yet, fix the bug :)
34:
35: Install the system, including the source sets:
36:
37: [[!template id=programlisting text="""
38: $ anita --workdir work --disk-size 4G --memory-size 256M \
39: --sets kern-GENERIC,modules,base,etc,comp,games,man,misc,tests,text,syssrc,src,sharesrc,gnusrc \
40: install /path/to/release/i386/
41: """]]
42:
43: replacing /path/to/release/i386/ with the actual release/i386
44: directory of the release you just built.
45:
46: ### Manual Environment Setup
47:
48: #### Creating the raw disk image
49:
50: To start our VM, we need some disk space to provide an emulated hard drive. For QEMU, by default, this is done through raw disk images. Therefore, the first step will be the creation of a disk image file. Here, we create a 2GB file, filled with zeros:
51:
52: [[!template id=programlisting text="""
53: $ dd if=/dev/zero of=netbsd-guest.img bs=1m count=2000
54: """]]
55:
56: /!\ if you want to mount the file image from within the host later through [[!template id=man name="vnconfig" section="8"]], it is recommended to use [[!template id=man name="dd" section="1"]] and not the *qemu-img* tool, as [[!template id=man name="vnd" section="4"]] does not support sparse disk image yet.
57:
58: Now that the disk image file is ready, we will need to install our system inside.
59:
60: #### Preparing the MBR, labels, and first stage boot loader
61:
62: Mount the image file as a [[!template id=man name="vnd" section="4"]] device. This will allow manipulating the image file just like a regular hard disk drive:
63:
64: [[!template id=programlisting text="""
65: # vnconfig -c vnd0 netbsd-guest.img
66: """]]
67:
68: #### Creating MBR
69:
70: Setup the MBR; it musts contain the NetBSD partition. This will be done interactively via [[!template id=man name="fdisk" section="8"]]:
71:
72: [[!template id=programlisting text="""
73: # fdisk -u -a -0 /dev/rvnd0
74: Disk: /dev/rvnd0d
75: [...]
76: Do you want to change our idea of what BIOS thinks? [n] *n*
77:
78: Partition 0:
79: <UNUSED>
80: The data for partition 0 is:
81: <UNUSED>
82: sysid: [0..255 default: 169] *press enter*
83: start: [0..255dcyl default: 63, 0dcyl, 0MB] *press enter*
84: size: [0..255dcyl default: 4095937, 255dcyl, 2000MB] *press enter*
85: bootmenu: [] *press enter*
86: Do you want to change the active partition? [n] *y*
87: Choosing 4 will make no partition active.
88: active partition: [0..4 default: 0] *press enter*
89: Are you happy with this choice? [n] *y*
90: We haven't written the MBR back to disk yet. This is your last chance.
91: Partition table:
92: 0: NetBSD (sysid 169)
93: start 63, size 4095937 (2000 MB, Cyls 0-254/245/55), Active
94: PBR is not bootable: All bytes are identical (0x00)
95: 1: <UNUSED>
96: 2: <UNUSED>
97: 3: <UNUSED>
98: Bootselector disabled.
99: First active partition: 0
100: Should we write new partition table? [n] *y*
101: """]]
102:
103: #### Editing labels
104:
105: Edit the labels, with [[!template id=man name="disklabel" section="8"]]. The example below will create:
106:
107: * label **a**, approximately 1.5GiB long -- will contain the future FFS / partition
108: * label **b**, 512MiB swap.
109:
110: [[!template id=programlisting text="""
111: # disklabel -e -I /dev/rvnd0
112: [...]
113: 4 partitions:
114: # size offset fstype [fsize bsize cpg/sgs]
115: a: 3047361 63 4.2BSD 0 0 0 # (Cyl. 0*- 1487)
116: b: 1048576 3047424 swap # (Cyl. 1488 - 1999)
117: d: 4096000 0 unused 0 0 # (Cyl. 0 - 1999)
118: """]]
119:
120: #### Copying first stage boot loader
121:
122: Lastly, we have to install the first stage boot loader, the one that will be able to read the second stage boot loader, which will reside in partition **a**. Use [[!template id=man name="installboot" section="8"]]:
123:
124: [[!template id=programlisting text="""
125: # installboot /dev/rvnd0a /usr/mdec/bootxx_ffsv2
126: """]]
127:
128: ### Format and mount the filesystem
129:
130: With [[!template id=man name="newfs" section="8"]], format label **a** in FFSv2:
131:
132: [[!template id=programlisting text="""
133: # newfs -O2 /dev/rvnd0a
134: /dev/rvnd0a: 1488.0MB (3047360 sectors) block size 16384, fragment size 2048
135: using 9 cylinder groups of 165.34MB, 10582 blks, 20544 inodes.
136: super-block backups (for fsck_ffs -b #) at:
137: 160, 338784, 677408, 1016032, 1354656, 1693280, 2031904, 2370528, 2709152,
138: """]]
139:
140: then [[!template id=man name="mount" section="8"]] it:
141:
142: [[!template id=programlisting text="""
143: # mkdir /tmp/netbsd-guest
144: # mount /dev/vnd0a /tmp/netbsd-guest
145: """]]
146:
147: ### Installing the system
148:
149:
150: ## Booting VMs
151:
152: Next, start two qemu virtual machines, one to run the kernel being
153: debugged (the "kgdb target") and another to run gdb (the "kgdb host").
154: They could be on different physical macines, but in this example, they
155: are run on the same physical machine, and the "-snapshot" qemu option
156: is used to avoid modifying the hard disk image so that it can be
157: shared between the host and target. First start the kgdb target,
158: enabling qemu's built-in GDB target stub on TCP port 1234:
159:
160: [[!template id=programlisting text="""
161: $ qemu -nographic -snapshot -hda work/wd0.img -gdb tcp::1234
162: """]]
163:
164: If you don't want everyone on the Internet to be able to debug your
165: target, make sure incoming connections on port 1234 are blocked in
166: your firewall.
167:
168: In a second terminal window, start the kgdb host:
169:
170: [[!template id=programlisting text="""
171: $ qemu -nographic -snapshot -hda work/wd0.img --net user --net nic,model=ne2k_pci
172: """]]
173:
174: Log in to the kgdb host as root and set up the network:
175:
176: [[!template id=programlisting text="""
177: login: root
178: # dhclient ne2
179: """]]
180:
181: If the sources you built using build.sh were in a location other than
182: /usr/src, set up a symlink from the place where they resided on the build
183: system to /usr/src (which is where they now reside on the kgdb host)
184: so that gdb can find them:
185:
186: [[!template id=programlisting text="""
187: # mkdir -p /path/to/parent/dir/of/your/sources
188: # ln -s /usr/src /path/to/parent/dir/of/your/sources/src
189: """]]
190:
191: Start gdb on the kgdb host and connect to the target:
192:
193: [[!template id=programlisting text="""
194: # gdb /netbsd
195: (gdb) target remote my.host.name:1234
196: """]]
197:
198: where my.host.name is the domain name or IP address of the
199: physical machine running the kgdb target qemu VM.
200:
201: Now you should be able to get a stack trace and start digging:
202:
203: [[!template id=programlisting text="""
204: (gdb) where
205: """]]
206:
207: If the stack trace prints very slowly (like 30 seconds per stack
208: frame), it's likely because you are using a version of qemu where
209: the user-mode networking code fails to disable the Nagle algorithm.
210: This is fixed in qemu-0.15.1nb5 in pkgsrc.
211:
212: ## Qemu usage
213:
214: There are couple useful commands to know when you are developing kernel features under the qemu.
215:
216: 1) Ctr-a-b will send a break to a NetBSD VM which will startup ddb kernel debugger.
217: 2) Ctr-a-c will switch to qemu monitor where user can use commands to save/restore vm from file.
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