Re: [Xen-devel] [RFC v3]Proposal to allow setting up shared memory areas between VMs from xl config file

[Stefano Stabellini <sstabellini@xxxxxxxxxx>]

On Thu, 20 Jul 2017, Zhongze Liu wrote:
> >> where:
> >>   @id                   can be any string that matches the regexp "[^ 
> >> \t\n,]+"
> >>                         and no logner than 128 characters
> >>   @begin/end            can be decimals or hexidemicals of the form 
> >> "0x20000".
> >>   @role                 can only be 'master' or 'slave'
> >>   @prot                 can be 'n', 'r', 'ro', 'w', 'wo', 'x', 'xo', 'rw', 
> >> 'rx',
> >>                         'wx' or 'rwx'. Default is 'rw'.
> >>   @arm_shareattr        can be 'inner' our 'outter', this will be ignored 
> >> and
> >>                         a warning will be printed out to the screen if it
> >>                         is specified in an x86 HVM config file.
> >>                         Default is 'inner'
> >>   @arm_outer_cacheattr  can be 'uc', 'wt', 'wb', 'bufferable' or 'wa', 
> >> this will
> >>                         be ignored and a warning will be printed out to the
> >>                         screen if it is specified in an x86 HVM config 
> >> file.
> >>                         Default is 'inner'
> >>   @arm_inner_cacheattr  can be 'uc', 'wt', 'wb', 'bufferable' or 'wa'. 
> >> Default
> >>                         is 'wb'.
> >
> > I don't think we need both @arm_outer_cacheattr and
> > @arm_inner_cacheattr: a single @arm_cacheattr should suffice.
> >
> > Also, we need to explain what each of these values mean. Instead, I
> > would only say that today we only support write-back:
> >
> > @arm_cacheattr  Only 'wb' (write-back) is supported today.
> >
> > In the code I would check that arm_cacheattr is either missing, or set
> > to 'wb'. Throw an error in all other cases.
> 
> I'm not sure whether I should first list out all the flags that are *supposed
> to be* accepted and then mark some of the flags unavailable or just simply
> list only the flags that are currently available.

I suggested to only mention 'wb' exactly to avoid having to list all the
possible and potential settings. Easier to only specify the one we
intend to support now.

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