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Re: [PATCH v3 13/19] xen/arm: Move fixmap definitions in a separate header



Hi Stefano,

On 05/04/2022 22:12, Stefano Stabellini wrote:
+/* Map a page in a fixmap entry */
+extern void set_fixmap(unsigned map, mfn_t mfn, unsigned attributes);
+/* Remove a mapping from a fixmap entry */
+extern void clear_fixmap(unsigned map);
+
+#endif /* __ASSEMBLY__ */
+
+#endif /* __ASM_FIXMAP_H */


It is a good idea to create fixmap.h, but I think it should be acpi.h to
include fixmap.h, not the other way around.

As I wrote in the commit message, one definition in fixmap.h rely on define from acpi.h (i.e NUM_FIXMAP_ACPI_PAGES). So if we don't include it, then user of FIXMAP_PMAP_BEGIN (see next patch) will requires to include acpi.h in order to build.

Re-ordering the values would not help because the problem would exactly be the same but this time the acpi users would have to include pmap.h to define NUM_FIX_PMAP.


The appended changes build correctly on top of this patch.

That's expected because all the users of FIXMAP_ACPI_END will be including acpi.h. But after the next patch, we would need pmap.c to include acpi.h.

I don't think this would be right (and quite likely you would ask why
this is done). Hence this approach.

Cheers,

--
Julien Grall



 


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