Re: [Xen-ia64-devel] [PATCH][RFC]copy_from/to_guest

[Tristan Gingold <Tristan.Gingold@xxxxxxxx>]

Le Jeudi 10 Août 2006 15:15, Kouya SHIMURA a écrit :
> Hi all,
>
> This patch fixes the copy_from/to_guest problem.
> As Akio reported, modularised netback causes dom0's down.
>
> The following process is happened in gnttab_transfer()@
> xen/common/grant_table.c:
>
>   gnttab_transfer()
>    => steal_page()
>      => assign_domain_page_cmpxchg_rel()
>        => domain_page_flush()
>          => domain_flush_vtlb_all()   // all TLBs are flushed
>    ...
>    => __copy_to_guest_offset()                // always fail to copy
>
> The embedded netback module has no problem because it uses TR pinned
> data.  But modularised one is out of TR. So copy_from/to_guest issue
> must be solved in order to modularise drivers.
>
> Attached patch fixes copy_from/to_guest issue for modularized netback.
> But I think this implementation is not beautiful.
Indeed.

I am planning to port xencomm from xen-ppc to xen-ia64.  This will make an 
incompatible change but will definitly get rid of these problems.

Seems to be more urgent than I thought!

Tristan.

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