Stephan Creutz
2007-Jan-25 17:53 UTC
[Xen-devel] the cause of invalid entries in physical-to-machine table
Hi, I am currently trying to understand the details of live-migration by looking at the code xc_linux_save.c in libxc and writing a simple program to make things more clear. The program memory maps all mfns which are used for the pfn to mfn list, goes through all pfns, resolves each pfn to a mfn and tries to memory map each of them to read its content. One thing I noticed are invalid physical-to-machine list entries (list entries where the resulting mfn equals INVALID_P2M_ENTRY and xc_map_foreign_range failes). I wonder what are the possible causes for invalid entries in the pfn to mfn list. One cause I can think of are pfns that are reserved for Xen itself, but what are the other ones? BTW: as far as I understand, xc_map_foreign_range should use the size 1 instead of PAGE_SIZE to get the shared info page and live_p2m_frame_list_list because this function expects the size in multiples of the page size not in bytes. Stephan _______________________________________________ Xen-devel mailing list Xen-devel@lists.xensource.com http://lists.xensource.com/xen-devel
Stephan Creutz
2007-Feb-06 12:22 UTC
Re: [Xen-devel] [Solved] the cause of invalid entries in physical-to-machine table
On Thu, 25 Jan 2007 18:53:10 +0100 Stephan Creutz <stephan.creutz@inf.tu-dresden.de> wrote:> I am currently trying to understand the details of live-migration by > looking at the code xc_linux_save.c in libxc and writing a simple > program to make things more clear. > > The program memory maps all mfns which are used for the pfn to mfn > list, goes through all pfns, resolves each pfn to a mfn and tries to > memory map each of them to read its content. One thing I noticed are > invalid physical-to-machine list entries (list entries where the > resulting mfn equals INVALID_P2M_ENTRY and xc_map_foreign_range > failes). I wonder what are the possible causes for invalid entries in > the pfn to mfn list. One cause I can think of are pfns that are > reserved for Xen itself, but what are the other ones?I used Xen 3.0.3-1 (which forgot to mention in the original mail). After Upgrading to version 3.0.4-1 the invalid entries disappeared. Stephan _______________________________________________ Xen-devel mailing list Xen-devel@lists.xensource.com http://lists.xensource.com/xen-devel