RE: [Xen-devel] running {MS/free}-DOS under XEN

["Petersson, Mats" <Mats.Petersson@xxxxxxx>]

> -----Original Message-----
> From: Tomas Kovacik [mailto:Tomas.Kovacik@xxxxxxxxxxxxxx] 
> Sent: 11 May 2007 10:03
> To: Petersson, Mats; xen-devel@xxxxxxxxxxxxxxxxxxx
> Subject: Re: [Xen-devel] running {MS/free}-DOS under XEN
> 
> Hi Mats.
> here is output from my xm info:
> [root@aero xen]# xm info
> host                   : aero
> release                : 2.6.20-1.2316.fc5xen
> version                : #1 SMP Fri Apr 27 19:36:52 EDT 2007
> machine                : x86_64
> nr_cpus                : 8
> nr_nodes               : 1
> sockets_per_node       : 2
> cores_per_socket       : 2
> threads_per_core       : 2
> cpu_mhz                : 2992
> hw_caps                : 
> bfebfbff:20100800:00000000:00000180:0000e4bd:00000000:00000001
> total_memory           : 3070
> free_memory            : 272
> xen_major              : 3
> xen_minor              : 0
> xen_extra              : .3-0-1.2316.fc5
> xen_caps               : xen-3.0-x86_64 hvm-3.0-x86_32 
> hvm-3.0-x86_32p hvm-3.0-x86_64
> xen_pagesize           : 4096
> platform_params        : virt_start=0xffff800000000000
> xen_changeset          : unavailable
> cc_compiler            : gcc version 4.1.1 20070105 (Red Hat 4.1.1-51)
> cc_compile_by          : brewbuilder
> cc_compile_domain      : build.redhat.com
> cc_compile_date        : Fri Apr 27 18:52:28 EDT 2007
> xend_config_format     : 2
> 
> do you know how could I install newer version of XEN, as you 
> mentioned xen-3.1-testing, in fedora core I use? i tried yum 
> install xen but it does not give me any newer version. do you 
> know where could i find i.e. repositories for yum(which would 
> be more confortable) or sources or package i could use? 

Ehm, no I don't know of any FC compatible archive for the latest 3.1
version. 

There is a 3.0.4 version available, built as an RPM for FC5, which
should be a noticable improvement on your 3.0.1 version:
http://www.xensource.com/download/index_3.0.4.html


> as you can see, i use Intel processors, which might be the 
> problem as you mentioned... 
> the thing is, i need DOS to run pharlab under it. i used qemu 
> before. I run DOS successfully, but than when i was trying to 
> run pharlab, it died with some other problem i cannot find 
> even mentioned on internet, as pharlab is not usual software 
> to use(it is kind of telecommunication switching centre 
> running on proprietary HW up on DOS)

PharLap is a "DOS-Extender", which means that it does use tricks
involving real-to-potected mode excursions. I don't know if it assumes
that segment registers will remain in place after those excursions - if
that's the case, then you'd have problems using it on Intel at the
moment, I think. 

There are several improvements in 3.1 that will make this "more likely
to work", but I wouldn't hold my breath. For a version after 3.1, there
will be a modified way of running real-mode on Intel processors, and
that will almost certainly achieve better compatibility with real
hardware. 

--
Mats
> any idea?
> THANKS. TOMAS
> 
> Petersson, Mats wrote: 
> 
>        
>       
>         
> 
>               -----Original Message-----
>               From: xen-devel-bounces@xxxxxxxxxxxxxxxxxxx 
>               [mailto:xen-devel-bounces@xxxxxxxxxxxxxxxxxxx] 
> On Behalf Of 
>               Tomas Kovacik
>               Sent: 10 May 2007 10:00
>               To: xen-devel@xxxxxxxxxxxxxxxxxxx
>               Subject: [Xen-devel] running {MS/free}-DOS under XEN
>               
>               Hi there.
>               I was looking around for a log time but I did 
> not find any 
>               user who would be able to run MS-DOS or freeDOS 
> under Xen. I 
>               use vmlinuz-2.6.20-1.2316.fc5xen kernel and 
> when I try to 
>               boot MS-DOS 7.1 it freezes with message shown 
> in attachement 
>               1. Also freeDOS freezes with message as in attachement2.
>               I tried to install these two systems from the 
> same iso image 
>               under qemu and it went OK so it seems that XEN 
> there is some 
>               issue with XEN and DOS running together.
>                   
> 
>       
>       Which version of Xen is this ("xm info" will give you 
> version numbers),
>       and is it an AMD or Intel processor you're using?
>       
>       I have recently (and succcessfully) run MS-DOS 6.22c on 
> an AMD-V capable
>       processor with xen-unstable, changeset circa 14800. I 
> expect this will
>       work on the latest xen-3.1-testing version as well. 
> Whether it works on
>       older versions, I'll let you figure out. 
>       
>       On Intel processors, there is a potential problemm in that these
>       processors don't support native real-mode in 
> virtualized mode. This
>       means that the guest has to trick around with 
> "vm86-mode", which causes
>       problems particularly with dos-extenders that switch 
> from real mode to
>       protected mode and back again [the real problem here is 
> maintaining the
>       extended segment values that may have been set during 
> the excursion to
>       protected mode - if there is no segment values 
> "expected to survive" the
>       transition, it should work just fine to switch between 
> modes on Intel
>       processors too]. 
>       
>       --
>       Mats
>         
> 
>                
>               
>               could somebody help me to run some version od 
> DOS under XEN? 
>               thank you very much.
>               TOMAS KOVACIK
>               
>               
>                   
> 
>       
>       
>         
> 
> 
> 



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