Annotation of wikisrc/netbsd_kernel_development_setup.mdwn, revision 1.7

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

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