On 26.04.2024 08:30, Henry Wang wrote: > On 4/26/2024 2:21 PM, Jan Beulich wrote: >> On 26.04.2024 05:14, Henry Wang wrote: >>> --- a/xen/include/public/hvm/params.h >>> +++ b/xen/include/public/hvm/params.h >>> @@ -76,6 +76,7 @@ >>> */ >>> #define HVM_PARAM_STORE_PFN 1 >>> #define HVM_PARAM_STORE_EVTCHN 2 >>> +#define HVM_PARAM_MAGIC_BASE_PFN 3 >>> >>> #define HVM_PARAM_IOREQ_PFN 5 >> Considering all adjacent values are used, it is overwhelmingly likely that >> 3 was once used, too. Such re-use needs to be done carefully. Since you >> need this for Arm only, that's likely okay, but doesn't go without (a) >> saying and (b) considering the possible future case of dom0less becoming >> arch-agnostic, or hyperlaunch wanting to extend the scope. Plus (c) imo >> this also needs at least a comment, maybe even an #ifdef, seeing how x86- >> focused most of the rest of this header is. > > Thanks for the feedback. These make sense. I think probably > dom0less/hyperlaunch will have similar use cases so the number 3 can be > reused at that time. Therefore, in v2, I will add more description in > commit message, a comment on top of this macro and protect it with > #ifdef. Hope this will address your concern. Thanks.
FTAOD: If you foresee re-use by hyperlaunch, re-using a previously used number may need re-considering. Which isn't to say that number re-use is excluded here, but it would need at least figuring out (and then stating) what exactly the number was used for and until when. Jan
