hey gang, just an odd question. I do a lot of cross compiling of software, all for x86, and got to thinking. It would be a LOT easier to setup a VM that thinks it''s an i(3|4|5|)86 instead of building separate tool chains. Does anyone know if I can make a xen machine think it is something other then what the host is, within x86 that is. _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
> > hey gang, just an odd question. I do a lot of cross compiling of > software, all for x86, and got to thinking. It would be a LOT > easier to > setup a VM that thinks it''s an i(3|4|5|)86 instead of > building separate > tool chains. Does anyone know if I can make a xen machine think it is > something other then what the host is, within x86 that is. >Hi Jason, Kind of :) I''m the sys admin for a software development team of around 70 or so. We have a series of server(s) that the guys build software on directly. Its all Linux (FC) based Java, C & C++ stuff. Recently, we''ve been getting new x86_64 boxes in the door and I had the same ?problem/idea?. My experiences so far... Xen won''t allow you to run say a 64bit DomO and have a 32bit DomU beneath it. They all have to be 64 or 32bit. Don''t know the true intricacies of why, (IIRC to do with how 64 and 32bit machines access memory) but you can''t. Haven''t tested VMware properly regarding this yet, but due to its different approach to virtualisation, it may be possible (if so I could be doing some serious migration work soon :). Subsequently, no, you can''t have a DomU think its something different (arch-wise). The kernels (DomO & DomU) have to be of the same arch so if the DomO is 64bit, your DomU has to be too. This is a problem for us when building apps (all of ours are for embedded 32bit targets). To get around these issues, I presently... # Generally run 64bit. Most of my DomO''s are x64_64 FC4/5 boxes. # Use a SSH startup hack (introduce setarch into the initscript) so that all clients that connect get a 32bit session. This works surprisingly well and stops nasty uname issues (their session always (presuming access via SSH) thinks its 32bit). # Create a 32bit template DomU. I have a series of *clean* DomU templates (created using yum into a chroot on a 32bit machine), that I use when creating a new 32bit DomU. I just copy the lot across to a new LVM based VBD, copy across the appropriate 64bit kernel and modules from the DomO (I keep kernels and modules for both on my DomO just in case), change the usual settings and light it up. Add in the SSH hack and you have to all intents and purposes, a 32bit DomU beneath a 64bit DomO. That''s about it. Its kind of messy, but it works. It would be nice to just use any architecture, but... (Wonder if VT based Xen Doms can be mixed and matched... Hmmmm....) HTH Dan -- Dan Hawker Linux System Administrator Astrium -- This email is for the intended addressee only. If you have received it in error then you must not use, retain, disseminate or otherwise deal with it. Please notify the sender by return email. The views of the author may not necessarily constitute the views of Astrium Limited. Nothing in this email shall bind Astrium Limited in any contract or obligation. Astrium Limited, Registered in England and Wales No. 2449259 Registered Office: Gunnels Wood Road, Stevenage, Hertfordshire, SG1 2AS, England _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
Ah, the ssh idea is a good one! Have you tried doing anything along the lines of making the machine think it is an i386 instead of a 686? I do most of my builds for boxes that are 486 compatible (Soekris, ELan chips). HAWKER, Dan wrote:>> hey gang, just an odd question. I do a lot of cross compiling of >> software, all for x86, and got to thinking. It would be a LOT >> easier to >> setup a VM that thinks it''s an i(3|4|5|)86 instead of >> building separate >> tool chains. Does anyone know if I can make a xen machine think it is >> something other then what the host is, within x86 that is. >> >> > > Hi Jason, > > Kind of :) > > I''m the sys admin for a software development team of around 70 or so. We > have a series of server(s) that the guys build software on directly. Its all > Linux (FC) based Java, C & C++ stuff. > > Recently, we''ve been getting new x86_64 boxes in the door and I had the same > ?problem/idea?. My experiences so far... > > Xen won''t allow you to run say a 64bit DomO and have a 32bit DomU beneath > it. They all have to be 64 or 32bit. Don''t know the true intricacies of why, > (IIRC to do with how 64 and 32bit machines access memory) but you can''t. > Haven''t tested VMware properly regarding this yet, but due to its different > approach to virtualisation, it may be possible (if so I could be doing some > serious migration work soon :). > > Subsequently, no, you can''t have a DomU think its something different > (arch-wise). The kernels (DomO & DomU) have to be of the same arch so if the > DomO is 64bit, your DomU has to be too. This is a problem for us when > building apps (all of ours are for embedded 32bit targets). > > To get around these issues, I presently... > > # Generally run 64bit. Most of my DomO''s are x64_64 FC4/5 boxes. > # Use a SSH startup hack (introduce setarch into the initscript) so that all > clients that connect get a 32bit session. This works surprisingly well and > stops nasty uname issues (their session always (presuming access via SSH) > thinks its 32bit). > # Create a 32bit template DomU. I have a series of *clean* DomU templates > (created using yum into a chroot on a 32bit machine), that I use when > creating a new 32bit DomU. I just copy the lot across to a new LVM based > VBD, copy across the appropriate 64bit kernel and modules from the DomO (I > keep kernels and modules for both on my DomO just in case), change the usual > settings and light it up. Add in the SSH hack and you have to all intents > and purposes, a 32bit DomU beneath a 64bit DomO. > > That''s about it. Its kind of messy, but it works. It would be nice to just > use any architecture, but... > > (Wonder if VT based Xen Doms can be mixed and matched... Hmmmm....) > > HTH > > Dan > -- > > Dan Hawker > Linux System Administrator > Astrium > >_______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
> > Ah, the ssh idea is a good one! Have you tried doing anything along > the lines of making the machine think it is an i386 instead > of a 686? I > do most of my builds for boxes that are 486 compatible (Soekris, ELan > chips). >Thanks :) It came about as I started simply wrapping bash, but it kept throwing up the occasional error which I didn''t like much. I thought of/stumbled into the SSH approach when I was looking at initscripts for some reason or another. Can''t say I have. The target(s) are all 686 or above so I haven''t needed to. Just done a quick *man setarch* and the man page isn''t very exhaustive, so you may need to do some digging/experimenting to get it to realise different subsets of the x86 architecture. Good luck Dan -- Dan Hawker Linux System Administrator Astrium -- This email is for the intended addressee only. If you have received it in error then you must not use, retain, disseminate or otherwise deal with it. Please notify the sender by return email. The views of the author may not necessarily constitute the views of Astrium Limited. Nothing in this email shall bind Astrium Limited in any contract or obligation. Astrium Limited, Registered in England and Wales No. 2449259 Registered Office: Gunnels Wood Road, Stevenage, Hertfordshire, SG1 2AS, England _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users