I want to put Xen on some 2GB hosts and am exploring the balloon mechansism. If I try to inflate the balloon more than 32768 pages at a time, the guest OS gets an oops: Unable to handle kernel NULL pointer dereference at virtual address 00000000 Deflating the balloon crashes the guest: <1>bd240 debug: deflate balloon called for fa0 pages Kernel panic: Failed mmu update: c019a3c0, 2048 Xen and DOM0 keep on running fine :-) Is deflation required? Or does Xen hand out pages on demand as guests need them? Is the linux config setting HIGHMEM4G supported? If not, can Xen itself see all 2GB and hand out independent 800MB chunks to guests? Domain creation works just fine with today''s pull. Thanks! I saw that recent CD-ROM post, my CD-ROM works fine. I can use a CD as a root partition. ------------------------------------------------------- SF.Net is sponsored by: Speed Start Your Linux Apps Now. Build and deploy apps & Web services for Linux with a free DVD software kit from IBM. Click Now! http://ads.osdn.com/?ad_id=1356&alloc_id=3438&op=click _______________________________________________ Xen-devel mailing list Xen-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/xen-devel
On 16 Feb 2004, at 15:20, David Becker wrote:> > I want to put Xen on some 2GB hosts and am exploring the balloon > mechansism. If I try to inflate the balloon more than 32768 pages at a > time, the guest OS gets an oops: > Unable to handle kernel NULL pointer dereference at virtual address > 00000000 > > Deflating the balloon crashes the guest: > <1>bd240 debug: deflate balloon called for fa0 pages > Kernel panic: Failed mmu update: c019a3c0, 2048Currently Xen doesn''t fully support (some basic support exists) HIGHMEM. As a result, each XenoLinux can at most have 896-64=832M memory. Besides, it has been quite a long time that no one has ever laid a finger on ''balloon'' tool. It''s very likely broken, thus not a good start point for you to play with Xen & XenoLinux.> Xen and DOM0 keep on running fine :-) > > Is deflation required? Or does Xen hand out pages on demand as guests > need them?Deflation is not required. You give the memory you want to allocate for a particular domain and Xen will try to get all the page frames (i.e. real machine memory pages) reserved for this domain. Then it''s domain''s own responsibility to use the allocated memory properly.> Is the linux config setting HIGHMEM4G supported? If not, can Xen > itself > see all 2GB and hand out independent 800MB chunks to guestsCurrently not supported but not too much too add, mainly involving modification to the domain building process. -- Bin ------------------------------------------------------- SF.Net is sponsored by: Speed Start Your Linux Apps Now. Build and deploy apps & Web services for Linux with a free DVD software kit from IBM. Click Now! http://ads.osdn.com/?ad_id=1356&alloc_id=3438&op=click _______________________________________________ Xen-devel mailing list Xen-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/xen-devel
> Besides, it has been quite a long time that no one has ever laid a > finger on > ''balloon'' tool. It''s very likely broken, thus not a good start point > for you to > play with Xen & XenoLinux.I''m kinda not surprised that the balloon driver has rotted, as no-one has tested it in ages. I have a design for how memory allocation *should* work if anyone is interested in implementing it properly. (It''s not hard, just not fun, hence we haven''t looked at it recently) > Is the linux config setting HIGHMEM4G supported? If not, can Xen> > itself > > see all 2GB and hand out independent 800MB chunks to guests > > Currently not supported but not too much too add, mainly involving > modification > to the domain building process.No, the above is incorrect. Xen should be able to see up to 4GB just fine, and be able to hand it out to multiple guests. Xenolinux does not support HIGHMEM4G, but it shouldn''t be too hard to add the support back in if anyone is interested (the arch/i386 code should basically just work, but got ripped out for expedience in the early days of Xenolinux, and hasn''t been put back). HIGHMEM64G (PAE36) will be a lot more work to implement, and we have no plans at present. x86_64 will likely happen first. Best, Ian ------------------------------------------------------- SF.Net is sponsored by: Speed Start Your Linux Apps Now. Build and deploy apps & Web services for Linux with a free DVD software kit from IBM. Click Now! http://ads.osdn.com/?ad_id=1356&alloc_id=3438&op=click _______________________________________________ Xen-devel mailing list Xen-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/xen-devel