On Wed, Aug 21, 2013 at 02:35:36PM +0200, H. Peter Anvin wrote: > Global symbols are inaccessible in physical mode. Even if they are embedded in the assembler code and use GLOBAL(paging_enabled) ? > > This is incidentally yet another example of "PV/weird platform violence", since in their absence it would be trivial to work around this by using segmentation. I don't follow why it could not. Why can't there be a __pa_symbol(paging_enabled) that is used. Won't that in effect allow you to check the contents of that 'global constant' even when you don't have paging enabled? > >>As mentioned above, on 32bit before paging is enabled, we have to > >>access variables > >>with pa. So introduce a "bool is_phys" parameter to extend_brk(), and > >>convert va > >>to pa is it is true. > > > >Could you do it differently? Meaning have a global symbol > >(paging_enabled) which will be used by most of the functions you > >changed in this patch and the next ones? It would naturally be enabled > >when paging is on and __va addresses can be used. > > > >That could also be used in the printk case to do a BUG_ON before paging > >is enabled on 32bit. Or perhaps use a different code path to deal with > >using __pa address. > > > >? -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>