qemu-doc.html

qemu虚拟机代码

Dump 80 16 bit values at the start of the video memory.

<PRE>
(qemu) xp/80hx 0xb8000
0x000b8000: 0x0b50 0x0b6c 0x0b65 0x0b78 0x0b38 0x0b36 0x0b2f 0x0b42
0x000b8010: 0x0b6f 0x0b63 0x0b68 0x0b73 0x0b20 0x0b56 0x0b47 0x0b41
0x000b8020: 0x0b42 0x0b69 0x0b6f 0x0b73 0x0b20 0x0b63 0x0b75 0x0b72
0x000b8030: 0x0b72 0x0b65 0x0b6e 0x0b74 0x0b2d 0x0b63 0x0b76 0x0b73
0x000b8040: 0x0b20 0x0b30 0x0b35 0x0b20 0x0b4e 0x0b6f 0x0b76 0x0b20
0x000b8050: 0x0b32 0x0b30 0x0b30 0x0b33 0x0720 0x0720 0x0720 0x0720
0x000b8060: 0x0720 0x0720 0x0720 0x0720 0x0720 0x0720 0x0720 0x0720
0x000b8070: 0x0720 0x0720 0x0720 0x0720 0x0720 0x0720 0x0720 0x0720
0x000b8080: 0x0720 0x0720 0x0720 0x0720 0x0720 0x0720 0x0720 0x0720
0x000b8090: 0x0720 0x0720 0x0720 0x0720 0x0720 0x0720 0x0720 0x0720
</PRE>

</UL>

<DT><SAMP>`p or print/fmt expr'</SAMP>
<DD>
Print expression value. Only the <VAR>format</VAR> part of <VAR>fmt</VAR> is
used.

<DT><SAMP>`sendkey keys'</SAMP>
<DD>
Send <VAR>keys</VAR> to the emulator. Use <CODE>-</CODE> to press several keys
simultaneously. Example:

<PRE>
sendkey ctrl-alt-f1
</PRE>

This command is useful to send keys that your graphical user interface
intercepts at low level, such as <CODE>ctrl-alt-f1</CODE> in X Window.

<DT><SAMP>`system_reset'</SAMP>
<DD>
Reset the system.

<DT><SAMP>`usb_add devname'</SAMP>
<DD>
Plug the USB device devname to the QEMU virtual USB hub. <VAR>devname</VAR>
is either a virtual device name (for example <CODE>mouse</CODE>) or a host
USB device identifier. Host USB device identifiers have the following
syntax: <CODE>host:bus.addr</CODE> or <CODE>host:vendor_id:product_id</CODE>.

<DT><SAMP>`usb_del devname'</SAMP>
<DD>
Remove the USB device <VAR>devname</VAR> from the QEMU virtual USB
hub. <VAR>devname</VAR> has the syntax <CODE>bus.addr</CODE>. Use the monitor
command <CODE>info usb</CODE> to see the devices you can remove.

</DL>



<H3><A NAME="SEC14" HREF="qemu-doc.html#TOC14">3.5.2 Integer expressions</A></H3>

<P>
The monitor understands integers expressions for every integer
argument. You can use register names to get the value of specifics
CPU registers by prefixing them with <EM>$</EM>.




<H2><A NAME="SEC15" HREF="qemu-doc.html#TOC15">3.6 Disk Images</A></H2>

<P>
Since version 0.6.1, QEMU supports many disk image formats, including
growable disk images (their size increase as non empty sectors are
written), compressed and encrypted disk images.




<H3><A NAME="SEC16" HREF="qemu-doc.html#TOC16">3.6.1 Quick start for disk image creation</A></H3>

<P>
You can create a disk image with the command:

<PRE>
qemu-img create myimage.img mysize
</PRE>

<P>
where <VAR>myimage.img</VAR> is the disk image filename and <VAR>mysize</VAR> is its
size in kilobytes. You can add an <CODE>M</CODE> suffix to give the size in
megabytes and a <CODE>G</CODE> suffix for gigabytes.


<P>
See section <A HREF="qemu-doc.html#SEC18">3.6.3 <CODE>qemu-img</CODE> Invocation</A> for more information.




<H3><A NAME="SEC17" HREF="qemu-doc.html#TOC17">3.6.2 Snapshot mode</A></H3>

<P>
If you use the option <SAMP>`-snapshot'</SAMP>, all disk images are
considered as read only. When sectors in written, they are written in
a temporary file created in <TT>`/tmp'</TT>. You can however force the
write back to the raw disk images by using the <CODE>commit</CODE> monitor
command (or <KBD>C-a s</KBD> in the serial console).




<H3><A NAME="SEC18" HREF="qemu-doc.html#TOC18">3.6.3 <CODE>qemu-img</CODE> Invocation</A></H3>


<PRE>
usage: qemu-img command [command options]
</PRE>

<P>
The following commands are supported:
<DL COMPACT>

<DT><SAMP>`create [-e] [-b <VAR>base_image</VAR>] [-f <VAR>fmt</VAR>] <VAR>filename</VAR> [<VAR>size</VAR>]'</SAMP>
<DD>
<DT><SAMP>`commit [-f <VAR>fmt</VAR>] <VAR>filename</VAR>'</SAMP>
<DD>
<DT><SAMP>`convert [-c] [-e] [-f <VAR>fmt</VAR>] <VAR>filename</VAR> [-O <VAR>output_fmt</VAR>] <VAR>output_filename</VAR>'</SAMP>
<DD>
<DT><SAMP>`info [-f <VAR>fmt</VAR>] <VAR>filename</VAR>'</SAMP>
<DD>
</DL>

<P>
Command parameters:
<DL COMPACT>

<DT><VAR>filename</VAR>
<DD>
 is a disk image filename
<DT><VAR>base_image</VAR>
<DD>
is the read-only disk image which is used as base for a copy on
    write image; the copy on write image only stores the modified data

<DT><VAR>fmt</VAR>
<DD>
is the disk image format. It is guessed automatically in most cases. The following formats are supported:

<DL COMPACT>

<DT><CODE>raw</CODE>
<DD>
Raw disk image format (default). This format has the advantage of
being simple and easily exportable to all other emulators. If your file
system supports <EM>holes</EM> (for example in ext2 or ext3 on Linux),
then only the written sectors will reserve space. Use <CODE>qemu-img
info</CODE> to know the real size used by the image or <CODE>ls -ls</CODE> on
Unix/Linux.

<DT><CODE>qcow</CODE>
<DD>
QEMU image format, the most versatile format. Use it to have smaller
images (useful if your filesystem does not supports holes, for example
on Windows), optional AES encryption and zlib based compression.
<DT><CODE>cow</CODE>
<DD>
User Mode Linux Copy On Write image format. Used to be the only growable
image format in QEMU. It is supported only for compatibility with
previous versions. It does not work on win32.
<DT><CODE>vmdk</CODE>
<DD>
VMware 3 and 4 compatible image format.
<DT><CODE>cloop</CODE>
<DD>
Linux Compressed Loop image, useful only to reuse directly compressed
CD-ROM images present for example in the Knoppix CD-ROMs.
</DL>

<DT><VAR>size</VAR>
<DD>
is the disk image size in kilobytes. Optional suffixes <CODE>M</CODE>
(megabyte) and <CODE>G</CODE> (gigabyte) are supported 

<DT><VAR>output_filename</VAR>
<DD>
is the destination disk image filename 

<DT><VAR>output_fmt</VAR>
<DD>
 is the destination format

<DT><VAR>-c</VAR>
<DD>
indicates that target image must be compressed (qcow format only)
<DT><VAR>-e</VAR>
<DD>
indicates that the target image must be encrypted (qcow format only)
</DL>

<P>
Command description:


<DL COMPACT>

<DT><SAMP>`create [-e] [-b <VAR>base_image</VAR>] [-f <VAR>fmt</VAR>] <VAR>filename</VAR> [<VAR>size</VAR>]'</SAMP>
<DD>
Create the new disk image <VAR>filename</VAR> of size <VAR>size</VAR> and format
<VAR>fmt</VAR>. 

If <VAR>base_image</VAR> is specified, then the image will record only the
differences from <VAR>base_image</VAR>. No size needs to be specified in
this case. <VAR>base_image</VAR> will never be modified unless you use the
<CODE>commit</CODE> monitor command.

<DT><SAMP>`commit [-f <VAR>fmt</VAR>] <VAR>filename</VAR>'</SAMP>
<DD>
Commit the changes recorded in <VAR>filename</VAR> in its base image.

<DT><SAMP>`convert [-c] [-e] [-f <VAR>fmt</VAR>] <VAR>filename</VAR> [-O <VAR>output_fmt</VAR>] <VAR>output_filename</VAR>'</SAMP>
<DD>
Convert the disk image <VAR>filename</VAR> to disk image <VAR>output_filename</VAR>
using format <VAR>output_fmt</VAR>. It can be optionnaly encrypted
(<CODE>-e</CODE> option) or compressed (<CODE>-c</CODE> option).

Only the format <CODE>qcow</CODE> supports encryption or compression. The
compression is read-only. It means that if a compressed sector is
rewritten, then it is rewritten as uncompressed data.

Encryption uses the AES format which is very secure (128 bit keys). Use
a long password (16 characters) to get maximum protection.

Image conversion is also useful to get smaller image when using a
growable format such as <CODE>qcow</CODE> or <CODE>cow</CODE>: the empty sectors
are detected and suppressed from the destination image.

<DT><SAMP>`info [-f <VAR>fmt</VAR>] <VAR>filename</VAR>'</SAMP>
<DD>
Give information about the disk image <VAR>filename</VAR>. Use it in
particular to know the size reserved on disk which can be different
from the displayed size.
</DL>



<H3><A NAME="SEC19" HREF="qemu-doc.html#TOC19">3.6.4 Virtual FAT disk images</A></H3>

<P>
QEMU can automatically create a virtual FAT disk image from a
directory tree. In order to use it, just type:



<PRE>
qemu linux.img -hdb fat:/my_directory
</PRE>

<P>
Then you access access to all the files in the <TT>`/my_directory'</TT>
directory without having to copy them in a disk image or to export
them via SAMBA or NFS. The default access is <EM>read-only</EM>.


<P>
Floppies can be emulated with the <CODE>:floppy:</CODE> option:



<PRE>
qemu linux.img -fda fat:floppy:/my_directory
</PRE>

<P>
A read/write support is available for testing (beta stage) with the
<CODE>:rw:</CODE> option:



<PRE>
qemu linux.img -fda fat:floppy:rw:/my_directory
</PRE>

<P>
What you should <EM>never</EM> do:

<UL>
<LI>use non-ASCII filenames ;

<LI>use "-snapshot" together with ":rw:" ;

<LI>expect it to work when loadvm'ing ;

<LI>write to the FAT directory on the host system while accessing it with the guest system.

</UL>



<H2><A NAME="SEC20" HREF="qemu-doc.html#TOC20">3.7 Network emulation</A></H2>

<P>
QEMU can simulate several networks cards (NE2000 boards on the PC
target) and can connect them to an arbitrary number of Virtual Local
Area Networks (VLANs). Host TAP devices can be connected to any QEMU
VLAN. VLAN can be connected between separate instances of QEMU to
simulate large networks. For simpler usage, a non priviledged user mode
network stack can replace the TAP device to have a basic network
connection.




<H3><A NAME="SEC21" HREF="qemu-doc.html#TOC21">3.7.1 VLANs</A></H3>

<P>
QEMU simulates several VLANs. A VLAN can be symbolised as a virtual
connection between several network devices. These devices can be for
example QEMU virtual Ethernet cards or virtual Host ethernet devices
(TAP devices).




<H3><A NAME="SEC22" HREF="qemu-doc.html#TOC22">3.7.2 Using TAP network interfaces</A></H3>

<P>
This is the standard way to connect QEMU to a real network. QEMU adds
a virtual network device on your host (called <CODE>tapN</CODE>), and you
can then configure it as if it was a real ethernet card.


<P>
As an example, you can download the <TT>`linux-test-xxx.tar.gz'</TT>
archive and copy the script <TT>`qemu-ifup'</TT> in <TT>`/etc'</TT> and
configure properly <CODE>sudo</CODE> so that the command <CODE>ifconfig</CODE>
contained in <TT>`qemu-ifup'</TT> can be executed as root. You must verify
that your host kernel supports the TAP network interfaces: the
device <TT>`/dev/net/tun'</TT> must be present.


<P>
See section <A HREF="qemu-doc.html#SEC25">3.8 Direct Linux Boot</A> to have an example of network use with a
Linux distribution and section <A HREF="qemu-doc.html#SEC10">3.3 Invocation</A> to have examples of
command lines using the TAP network interfaces.




<H3><A NAME="SEC23" HREF="qemu-doc.html#TOC23">3.7.3 Using the user mode network stack</A></H3>

<P>
By using the option <SAMP>`-net user'</SAMP> (default configuration if no
<SAMP>`-net'</SAMP> option is specified), QEMU uses a completely user mode
network stack (you don't need root priviledge to use the virtual
network). The virtual network configuration is the following:



<PRE>

         QEMU VLAN      &#60;------&#62;  Firewall/DHCP server &#60;-----&#62; Internet
                           |          (10.0.2.2)
                           |
                           ----&#62;  DNS server (10.0.2.3)
                           |     
                           ----&#62;  SMB server (10.0.2.4)
</PRE>

<P>
The QEMU VM behaves as if it was behind a firewall which blocks all
incoming connections. You can use a DHCP client to automatically
configure the network in the QEMU VM. The DHCP server assign addresses
to the hosts starting from 10.0.2.15.


<P>
In order to check that the user mode network is working, you can ping
the address 10.0.2.2 and verify that you got an address in the range
10.0.2.x from the QEMU virtual DHCP server.


<P>
Note that <CODE>ping</CODE> is not supported reliably to the internet as it
would require root priviledges. It means you can only ping the local
router (10.0.2.2).


<P>
When using the built-in TFTP server, the router is also the TFTP
server.


<P>
When using the <SAMP>`-redir'</SAMP> option, TCP or UDP connections can be
redirected from the host to the guest. It allows for example to
redirect X11, telnet or SSH connections.




<H3><A NAME="SEC24" HREF="qemu-doc.html#TOC24">3.7.4 Connecting VLANs between QEMU instances</A></H3>

<P>
Using the <SAMP>`-net socket'</SAMP> option, it is possible to make VLANs
that span several QEMU instances. See section <A HREF="qemu-doc.html#SEC10">3.3 Invocation</A> to have a
basic example.




<H2><A NAME="SEC25" HREF="qemu-doc.html#TOC25">3.8 Direct Linux Boot</A></H2>

<P>
This section explains how to launch a Linux kernel inside QEMU without
having to make a full bootable image. It is very useful for fast Linux
kernel testing. The QEMU network configuration is also explained.



<OL>
<LI>

Download the archive <TT>`linux-test-xxx.tar.gz'</TT> containing a Linux
kernel and a disk image. 

<LI>Optional: If you want network support (for example to launch X11 examples), you

must copy the script <TT>`qemu-ifup'</TT> in <TT>`/etc'</TT> and configure
properly <CODE>sudo</CODE> so that the command <CODE>ifconfig</CODE> contained in
<TT>`qemu-ifup'</TT> can be executed as root. You must verify that your host
kernel supports the TUN/TAP network interfaces: the device
<TT>`/dev/net/tun'</TT> must be present.

When network is enabled, there is a virtual network connection between
the host kernel and the emulated kernel. The emulated kernel is seen
from the host kernel at IP address 172.20.0.2 and the host kernel is
seen from the emulated kernel at IP address 172.20.0.1.

<LI>Launch <CODE>qemu.sh</CODE>. You should have the following output:


<PRE>
&#62; ./qemu.sh 
Connected to host network interface: tun0
Linux version 2.4.21 ([e-mail]) (gcc version 3.2.2 20030222 @/(Red Hat @/Linux 3.2.2-5)) #5 Tue Nov 11 18:18:53 CET 2003
BIOS-provided physical RAM map:
 BIOS-e801: 0000000000000000 - 000000000009f000 (usable)
 BIOS-e801: 0000000000100000 - 0000000002000000 (usable)
32MB LOWMEM available.
On node 0 totalpages: 8192
zone(0): 4096 pages.
zone(1): 4096 pages.
zone(2): 0 pages.
Kernel command line: root=/dev/hda sb=0x220,5,1,5 ide2=noprobe ide3=noprobe ide4=noprobe @/ide5=noprobe console=ttyS0
ide_setup: ide2=noprobe
ide_setup: ide3=noprobe
ide_setup: ide4=noprobe
ide_setup: ide5=noprobe
Initializing CPU#0
Detected 2399.621 MHz processor.
Console: colour EGA 80x25
Calibrating delay loop... 4744.80 BogoMIPS
Memory: 28872k/32768k available (1210k kernel code, 3508k reserved, 266k data, 64k init, @/0k highmem)
Dentry cache hash table entries: 4096 (order: 3, 32768 bytes)
Inode cache hash table entries: 2048 (order: 2, 16384 bytes)
Mount cache hash table entries: 512 (order: 0, 4096 bytes)
Buffer-cache hash table entries: 1024 (order: 0, 4096 bytes)
Page-cache hash table entries: 8192 (order: 3, 32768 bytes)
CPU: Intel Pentium Pro stepping 03
Checking 'hlt' instruction... OK.
POSIX conformance testing by UNIFIX
Linux NET4.0 for Linux 2.4
Based upon Swansea University Computer Society NET3.039
Initializing RT netlink socket
apm: BIOS not found.
Starting kswapd
Journalled Block Device driver loaded
Detected PS/2 Mouse Port.
pty: 256 Unix98 ptys configured
Serial driver version 5.05c (2001-07-08) with no serial options enabled
ttyS00 at 0x03f8 (irq = 4) is a 16450
ne.c:v1.10 9/23/94 Donald Becker ([e-mail])
Last modified Nov 1, 2000 by Paul Gortmaker