Hi, Sorry for the formatting.
On Tue, 23 Apr 2019, 18:34 Stefano Stabellini, <sstabell...@kernel.org> wrote: > On Tue, 23 Apr 2019, Julien Grall wrote: > > Hi Stefano, > > > > On 4/22/19 11:42 PM, Stefano Stabellini wrote: > > > On Tue, 26 Feb 2019, Julien Grall wrote: > > > I am not sure about the suggestion of re-using the libfdt concept of > > > "mem_rsv", which is meant to be for the old /memreserve/. Today, libfdt > > > (at least our version of it) is not able to parse the new > > > reserved-memory bindings. I don't think it is a good idea to modify > > > libfdt for that. Also, the way we want to handle the old memreserve > > > regions is quite different from the way we want to handle > > > reserved-memory, right? I cannot see a way to improve this code using > > > mem_rsv at the moment. > > > > I didn't mean to extend mem_rsv in libfdt but extend consider_modules and > > dt_unreserved_regions to deal with /reserved-memory. Otherwise you > > may miss some cases (for instance you left out discard_initial_modules). > > > > By extending those two functions you don't have to teach everyone how to > skip > > /reserved-memory. > > I think I get your point now. Although I don't think it should be > correct for a bootloader to use a reserved-memory area to store a boot > module, I wouldn't be suprised if that happens, so it is better to be > prepared and extend dt_unreserved_regions. I'll do that. > Why wouldn't this be correct? It is nothing different /mem-reserve. > However, we would still need something like check_reserved_memory, > because we don't want setup_xenheap_mappings to be called on the > reserved-memory area (or a memory region including the reserved memory > area) in setup_mm. I don't think we can get away without it, but I can > simplify it. > Hmmm, setup_xenheap_mappings is only doing the mapping in page-tables allowing direct access in Xen. Are you worried of the memory attributes to be different in Xen? This would makes sense however setup_xenheap_mappings may still map the reserved-memory because it is using 1G mapping... This is pretty wrong and I have patches that should help to fix it. Also if you are concerned with /reserved-memory, then it should also be fixed for /mem-reserve as they are not different. However, this may break free_initmem as because we try to give back page to xenheap even if they are reserved. The memory management is quite a mess today. I hope to make it better with my upcoming series. Cheers,
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