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Re: [PATCH 03/12] xen: harmonize return types of hypercall handlers


  • To: Juergen Gross <jgross@xxxxxxxx>
  • From: Jan Beulich <jbeulich@xxxxxxxx>
  • Date: Mon, 18 Oct 2021 16:25:01 +0200
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  • Cc: Stefano Stabellini <sstabellini@xxxxxxxxxx>, Julien Grall <julien@xxxxxxx>, Volodymyr Babchuk <Volodymyr_Babchuk@xxxxxxxx>, Andrew Cooper <andrew.cooper3@xxxxxxxxxx>, George Dunlap <george.dunlap@xxxxxxxxxx>, Ian Jackson <iwj@xxxxxxxxxxxxxx>, Wei Liu <wl@xxxxxxx>, Roger Pau Monné <roger.pau@xxxxxxxxxx>, Christopher Clark <christopher.w.clark@xxxxxxxxx>, xen-devel@xxxxxxxxxxxxxxxxxxxx
  • Delivery-date: Mon, 18 Oct 2021 14:25:18 +0000
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On 18.10.2021 15:24, Juergen Gross wrote:
> On 18.10.21 13:55, Jan Beulich wrote:
>> On 15.10.2021 14:51, Juergen Gross wrote:
>>> Change the type of the cmd parameter for [do|compat]_kexec_op() to
>>> unsigned int, as this is more appropriate for the compat case.
>>
>> The change for the compat case is fine, but for native you change
>> behavior for callers passing values equaling valid KEXEC_CMD_*
>> modulo 2³².
> 
> TBH, I don't think this is really a problem. Or do you think there
> really is a user of this interface relying on a -ENOSYS in this
> case?

That's a secondary consideration of mine only. The primary one is
that invoking with an invalid sub-op should fail, such that in the
future we can assign meaning to the upper bits, if need be. See
their use for continuations in memory-op, for example.

Jan




 


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