[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [Xen-devel] Re: [PATCH] xen: add a comment for hypercall_xlat_continuation
>>> On 10.11.11 at 08:57, Ian Campbell <ian.campbell@xxxxxxxxxx> wrote: > # HG changeset patch > # User Ian Campbell <ian.campbell@xxxxxxxxxx> > # Date 1320911800 0 > # Node ID 3c6eaf62996dd26d7d0a055955d30bc6c7067f91 > # Parent e6af32ecb4483457d5ad9a7b674c18aaf20cc085 > xen: add a comment for hypercall_xlat_continuation > > The interface of this function is really rather complex and having reverse > engineered it for the N'th time I think it is time to write things down. > > Signed-off-by: Ian Campbell <ian.campbell@xxxxxxxxxx> Thanks for doing this! Acked-by: Jan Beulich <jbeulich@xxxxxxxx> > diff -r e6af32ecb448 -r 3c6eaf62996d xen/include/xen/compat.h > --- a/xen/include/xen/compat.h Tue Oct 18 14:15:09 2011 +0100 > +++ b/xen/include/xen/compat.h Thu Nov 10 07:56:40 2011 +0000 > @@ -185,6 +185,34 @@ static inline int name(k xen_ ## n *x, k > CHECK_FIELD_COMMON_(k, CHECK_NAME_(k, n ## __ ## f1 ## __ ## f2 ## __ > ## \ > f3, F2), n, f1.f2.f3) > > +/* > + * Translate a native continuation into a compat guest continuation. > + * > + * id: If non-NULL then points to an integer N between 0-5. Will be updated > + * with the value of the N'th argument to the hypercall. The N'th argument > must > + * not be subject to translation (i.e. cannot be referenced by @mask > below). > + * This option is useful for extracting the "op" argument or similar from > the > + * hypercall to enable further xlat processing. > + * > + * mask: Specifies which of the hypercall arguments require compat > translation. > + * bit 0 indicates that the 0'th argument requires translation, bit 1 > indicates > + * that the first argument requires translation and so on. Native and > compat > + * values for each translated argument are provided as @varargs (see > below). > + * > + * varargs: For each bit which is set in @mask the varargs contain a native > + * value (unsigned long) and a compat value (unsigned int). If the native > value > + * and compat value differ and the N'th argument is equal to the native > value > + * then that argument is replaced by the compat value. If the native and > compat > + * values are equal then no translation takes place. If the N'th argument > does > + * not equal the native value then no translation takes place. > + * > + * Any untranslated argument (whether due to not being requested in @mask, > + * native and compat values being equal or N'th argument not equalling > native > + * value) must be equal in both native and compat representations (i.e. the > + * native version cannot have any bits > 32 set) > + * > + * Return: Number of arguments which were actually translated. > + */ > int hypercall_xlat_continuation(unsigned int *id, unsigned int mask, ...); > > /* In-place translation functons: */ _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxxxxxxxx http://lists.xensource.com/xen-devel
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