HOWTO: build qemu from cvs (incl. accelerator)

notz · n00b Joined: 31 Aug 2004 Posts: 15 Location: Graz, Austria

goto to your portage overlay

AlterEgo · Veteran Joined: 25 Apr 2002 Posts: 1619

watashiwaotaku7 · n00b Joined: 26 Mar 2003 Posts: 70

When using qemu, trying to install windows xp it dies with "bus error" when trying to format the image as fat32 (or ntfs) I invoke qemu with "qemu -user-net -enable-audio -m 384 -hda hd.img -cdrom /dev/hdc -boot d" and created the hd image by going to / and invoking "dd of=hd.img bs=1024 seek=30000000 count=0" my root partition is set as device /dev/md0 using md raid, is this what is causing my problem? I also tried making the image on a empty fat32 partition and replacing -hda hd.img with /mnt/hda/hd.img, can anyone tell me what I am doing wrong?

EDIT: FIXED! I removed the -m 384 argument, from what I can tell this is for using virtual memory only, and you must compile qemu with a certain flag in order for this to work, installing now.

bravecobra · Posted: Tue Mar 01, 2005 10:55 pm Post subject:

To have both access to internet and your local network from within qemu, check my blog: http://blog.bravecobra.com/index.php/linux/2005/02/25/emulating_an_os_with_qemu
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PraetorZero · Apprentice Joined: 11 Dec 2004 Posts: 239 Location: /home

Pardon my n00b-ness, but would this pull whatever is the current version in CVS when you emerge it? So... if I were to find at a later time a new version is out, all I would have to do is clear the cache and re-emerge qemu?

1der · Tux's lil' helper Joined: 06 Aug 2003 Posts: 99

I also got the same result as watashiwaotaku7.

What did u do to fix it ? What compile flag did you use?

running the old qemu (6.1) was fine.

watashiwaotaku7 · n00b Joined: 26 Mar 2003 Posts: 70

1der, per my edit, I removed -m 384, if you search there is a thread in portage and programming aobut qemu and the accelerator that talks about using some flag which causes qemu to use only virtual memory.

Having said that, I am still having problems but at least it is installed, everything is working fine, but for some reason it doesnt seem to be using system memory to run windows, which is causing it to be very very slow, I am only using 94 mb of memory total and I have 512 mb so I was hoping to have my emulated OS running on this too, how exactly do I do that? I also imagine other people will want to know since my slowdown running this on raid 0 is big enough, it must be worse with just a regular drive.

bravecobra · Posted: Thu Mar 03, 2005 4:33 am Post subject:

the -m 384 sets the amount of memory you want to assign to qemu. Note that this is the amount of memory you won't be able to use for your host then.
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notz · n00b Joined: 31 Aug 2004 Posts: 15 Location: Graz, Austria

the mem given to qemu should be lower than /dev/shm

watashiwaotaku7 · n00b Joined: 26 Mar 2003 Posts: 70

none /dev/shm tmpfs defaults , is my /dev/shm line, how do I edit this to change the size?

also,

has anyone experimented with different windows versions to see which is the most responsive?

how does qemu deal with graphics? (eg: does graphic rendering have the same type of slowdown as everything else or does it just use the native drivers to do everything?)

has anyone attempted to register their windows xp on qemu? I'm using an OEM version of windows from dell, and it tells me the registration key is invalid, how will the microsoft support staff feel about me trying to register and emulated version of XP?

jdgill0 · Posted: Thu Mar 03, 2005 11:38 pm Post subject:

Use the "size" option:

corefile · n00b Joined: 27 Jun 2002 Posts: 44

at6 · Posted: Sun Mar 06, 2005 12:41 am Post subject:

great howto.

qemu works like a charm. thanks!

best regards
marc
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bravecobra · Posted: Sun Mar 06, 2005 4:03 am Post subject:

You should be able to able all of that, following the guidelines. Maybe you need to adjust your smb.conf? I haven't tested this, but it should possible. The only thing you won't be able to do, is run services on the qemu host, unless you set upset a forwarding to your host's gateway.
As you can see in the screenshot (might be a little small), I was able to access my network through samba from within qemu and had access to the internet.
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pussi · l33t Joined: 08 May 2004 Posts: 727 Location: Finland

Note that if you are using udev, /dev/kqemu is not created automatically when you boot, and acceleration won't work.
( http://fabrice.bellard.free.fr/qemu/kqemu-doc.html#SEC4 )

If youre using udev you need to create the file yourself:

techiem2 · Posted: Tue Mar 08, 2005 8:24 pm Post subject:

The Howto is wonderful and worked fine.
I am having one problem though.

When I try to boot my old Win98SE vm, it dies with a Windows Protection Error.
Starting it with -no-kqemu works fine as before.

Any suggestions?

I'm currently trying to install win2k in a new vm to see if that works.

Mark II

pussi · l33t Joined: 08 May 2004 Posts: 727 Location: Finland

Koala Kid · Guru Joined: 09 May 2003 Posts: 382

Guys, how can I access my local files and directories from the guest OS ?
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techiem2 · Posted: Wed Mar 09, 2005 10:40 pm Post subject:

You have to setup the networking and use smb (at least from win) to access the host.
There's a link higher in the thread about how to set that up.

Direct access to the host fs would be a nice feature.

stonent · Veteran Joined: 07 Aug 2003 Posts: 1139 Location: Texas

Lejban · n00b Joined: 12 Dec 2003 Posts: 53 Location: Sweden

Koala Kid · Guru Joined: 09 May 2003 Posts: 382

Lejban · n00b Joined: 12 Dec 2003 Posts: 53 Location: Sweden

Debentoo_Gao · Posted: Sat Mar 12, 2005 11:36 am Post subject:

pussi · l33t Joined: 08 May 2004 Posts: 727 Location: Finland

I just realized that it don't work with me eiter :oops:

I know it should work as it reads in Qemu acceleration module manual, but for some reason it don't.