On 26/06/2019 21:39, Julien Grall wrote: > On 6/26/19 9:25 PM, Stefano Stabellini wrote: >> On Mon, 10 Jun 2019, Julien Grall wrote: >>> The ID map may clash with other parts of the Xen virtual memory layout. >>> At the moment, Xen is handling the clash by only creating a mapping to >>> the runtime virtual address before enabling the MMU. >>> >>> The rest of the mappings (such as the fixmap) will be mapped after the >>> MMU is enabled. However, the code doing the mapping is not safe as it >>> replace mapping without using the Break-Before-Make sequence. >>> >>> As the ID map can be anywhere in the memory, it is easier to remove all >>> the entries added as soon as the ID map is not used rather than adding >>> the Break-Before-Make sequence everywhere. >> >> I think it is a good idea, but I would ask you to mention 1:1 map >> instead of "ID map" in comments and commit messages because that is the >> wording we used in all comments so far (see the one in >> create_page_tables and mm.c). It is easier to grep and refer to if we >> use the same nomenclature. Note that I don't care about which >> nomenclature we decide to use, I am only asking for consistency. >> Otherwise, it would also work if you say it both way at least once: >> >> The ID map (1:1 map) may clash [...] > > I would rather drop the wording 1:1 as this is confusing. It is also > not trivial to find anything on google typing "1:1".
"one-to-one mapping", or "identity map" are both common terminology. 1:1 is a common representation for the former, whereas ID is not a abbreviation of "Identity". If you don't want to use 1:1, then you need to say "The identity map" to retain clarity. ~Andrew _______________________________________________ Xen-devel mailing list Xen-devel@lists.xenproject.org https://lists.xenproject.org/mailman/listinfo/xen-devel
