Re: [Xen-devel] libxl: vpl011: Fix hex to dec conversion of vuart_gfn in libxl__device_vuart_add

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

On 13/10/17 13:08, Jan Beulich wrote:
>>>> On 13.10.17 at 12:44, <bhupinder.thakur@xxxxxxxxxx> wrote:
>> In libxl__device_vuart_add vuart_gfn is getting stored as a hex value:
>>
>>> flexarray_append(ro_front, GCSPRINTF("%"PRI_xen_pfn, state->vuart_gfn));
>> However, xenstore reads this value as a decimal value and tries to map the
>> wrong address and fails.
> Is this generic or vuart specific code in xenstore that does so?
> Could you perhaps simply point me at the consuming side?
>
>> Introduced a new format string "PRIu_xen_pfn" which formats the value as a
>> decimal value.
> I ask because I'm not really happy about this addition, i.e. I'd
> prefer the read side to change.

Can the read side realistically change?

Its been decimal for a decade now, and there definitely is 3rd party
code which uses these values in xenstore (sadly).

Then again, the ring-ref key is listed as deprecated in our
documentation, without any reference describing which key should be used
instead.  It is also typically a grant reference, not a gfn, so
something wonky is definitely going on here.

~Andrew

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