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

[Juergen Gross <jgross@xxxxxxxx>]

On 18.10.21 16:25, Jan Beulich wrote:
> 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.
But this would mean to exclude such usage of upper bits for 32 bit
systems in case this difference should matter.


Juergen

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