[Xen-devel] Immediate kernel panic using gntdev device

[D Sundstrom <sunds@xxxxxxxxxx>]

Running under debian wheezy kernel 3.2.0-3-686-pae (32 bit), under Xen 4.1 HVM.

The linux PV drivers load and all appears to be fine.

I want to use the gntalloc device to allocate a page of memory from Domain A and then map that into Domain B using gntdev.  Both are unprivileged domains.  

Using Daniel DeGraaf's test program here: http://lists.xen.org/archives/html/xen-devel/2011-01/txtzDU6iZhTkB.txt

I can run the command to create a grant, but upon running the command to map the grant (from either the same domain or another DomU), the kernel immediately crashes with no diagnostic output.

Should I expect to be able to map grants in a DomU allocated in another DomU?

Example of running the test:

$  xenstore-read domid

8

$  thetestprogram

src-add <domid>       return gntref, address
map <domid> <ref>     return index, address
src-del <gntref>      no rv
gu <index>            no rv
unmap <address>       no rv
show                  print and change mapped items
This process bumps by 4000

src-add 8

src-add mapped 1372 at 0=0

show

00(-1217044480,0): current     4000    new    0

map 8 1372   

(immediately crashes the VM)

Thanks,

David

 

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