Re: [Xen-devel] Creating HVM guest by libxenguest

[Gihan Munasinghe <GMunasinghe@xxxxxxxxxxxxxx>]

Gary Pennington wrote:
> On Thu, Oct 02, 2008 at 09:36:47AM +0100, Gihan Munasinghe wrote:
>   
> > Hi
> >
> > I am new to developing for XEN. I wanted to crate a HVM using xencltr.h 
> > and xenguest.h.. Following is the code I got from while browsing
> > done by Mark McLoughlin <markmc@xxxxxxxxxx> and did some modification.
> > ============================================================================================ 
> >
> > #include <stdio.h>
> > #include <xenctrl.h>
> > #include <xenguest.h>
> >
> > #define MEM_MB 1024
> > #define IMAGE "/root/osimages/vmlinuz-2.6.24-19-xen"
> > #define INITRD NULL
> > #define CMDLINE ""
> > #define FEATURES NULL
> > #define FLAGS 0
> >
> > int
> > main(int argc, char **argv)
> > {
> > int xc_handle, ret;
> > uint32_t domid;
> > unsigned int store_evtchn, console_evtchn;
> > unsigned long store_mfn, console_mfn;
> > xen_domain_handle_t uuid = {
> >   0xb2, 0x93, 0x22, 0x1f,
> >   0x1a, 0xaa, 0x20, 0xac,
> >   0xbe, 0x36, 0xc4, 0xd7,
> >   0x6b, 0x73, 0x92, 0x1,
> > };
> >
> > xc_handle = xc_interface_open();
> > if (xc_handle == -1)
> >   {
> >     fprintf(stderr, "xc_interface_open() failed\n");
> >     return 1;
> >   }
> >
> > domid = 0;
> >
> > ret = xc_domain_create(xc_handle, 0, uuid, 0, &domid);
> > if (ret != 0)
> >   {
> >     fprintf(stderr, "xc_dom_linux_build() failed\n");
> >     goto fail;
> >   }
> >
> > store_evtchn = xc_evtchn_alloc_unbound(xc_handle, domid, 0);
> > if (store_evtchn < 0)
> >   {
> >     fprintf(stderr, "Failed to allocate xenstore event channel\n");
> >     goto fail;
> >   }
> >
> > console_evtchn = xc_evtchn_alloc_unbound(xc_handle, domid, 0);
> > if (console_evtchn < 0)
> >   {
> >     fprintf(stderr, "Failed to allocate console event channel\n");
> >     goto fail;
> >   }
> >
> > ret = xc_domain_setmaxmem(xc_handle, domid, MEM_MB << 10);
> > if (ret != 0)
> >   {
> >     fprintf(stderr, "xc_domain_set_maxmem() failed\n");
> >     goto fail;
> >   }
> >
> > ret = xc_domain_max_vcpus(xc_handle, domid, 1);
> > if (ret != 0)
> >   {
> >     fprintf(stderr, "xc_domain_max_vcpus() failed\n");
> >     goto fail;
> >   }
> >
> >
> > /*  ret = xc_linux_build(xc_handle, domid,524288,
> >                      IMAGE, INITRD,
> >                      CMDLINE, FEATURES, FLAGS,
> >                      store_evtchn, &store_mfn,
> >                      console_evtchn, &console_mfn);
> > */
> > ret = xc_hvm_build(xc_handle, domid, MEM_MB, IMAGE);                    
> > if (ret != 0)
> >   {
> >     fprintf(stderr, "xc_dom_linux_build() failed\n");
> >     goto fail;
> >   }
> >
> >
> > xc_interface_close(xc_handle);
> >   return 0;
> >
> > fail:
> > if (domid)
> >   {
> >     xc_evtchn_reset(xc_handle, domid);
> >     xc_domain_destroy(xc_handle, domid);
> >   }
> > xc_interface_close(xc_handle);
> > return 1;
> > }
> > ===============================================================
> >
> > When running this code I get the following error output
> >
> > VIRTUAL MEMORY ARRANGEMENT:
> > Loader:        00000000c0100000->00000000c0503000
> > TOTAL:         0000000000000000->0000000040000000
> > ENTRY ADDRESS: 00000000c0100000
> > Failed allocation for dom 12: 261952 extents of order 0
> > ERROR Internal error: Could not allocate memory for HVM guest.
> > (16 = Device or resource busy)
> > xc_dom_linux_build() failed
> >
> >     
> Looks like you don't have enough memory on your system to build a 1GB
> guest domain...
>
> It's trying to allocate 261952 4k pages (i.e. 1GB) and failing. You
> could reduce MEM_MB or try running your program on a system with more
> memory.
>   
I am running this code in a machine with has 8GB of ram.. But when I 
look at though virt-manager it says dom0 is using 8GB. I think that may 
be the problem. Is there any XEn setting or code change I need to do get 
the ram back off dom0
Thanks
Gihan
> Gary
>
>   
> > Could someone give me some insight to this, also is there any source 
> > codes or documentation that I can find on using low level xen interface..
> > Thanks
> > Gihan
> >
> >
> >
> >
> > _______________________________________________
> > Xen-devel mailing list
> > Xen-devel@xxxxxxxxxxxxxxxxxxx
> > http://lists.xensource.com/xen-devel
> >     
>   

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