[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] RE: [Xen-devel] [NEO 1:1] Nativedom 1:1 Mapping
I tried to change just boot_e820 but that wasn't enough since other code parts still use the original e820 later in the code, I could try to see if this code can be migrated to use boot_e820. It is also possible to use E820_reserve, and save the regions somewhere aside. Regarding the e820 manipulations, I do not agree, we need to perform a lot more tasks than what reserve_in_boot_e820() allow, the memory map could have holes at certain regions, the code in mm_early.c handles all kind of edge cases, I'm using nd_punch_e820_entry() for "punching" reserved areas in the e820 (I do not delete them, since nativedom_e820 is almost an exact mirror of e820), I use this function for other tasks as well (such as preparing nativedom_e820). The mm_early.c e820 functions are generic so they could be used elsewhere, it is a good infrastructure for e820 manipulations. For instance, there could be a reserved area somewhere in the middle of the RAM that you'll want to skip if you dedicate the region to the 1:1 allocator, when you build nativedom_e820 this region should be marked as reserved and be protected against NativeDom accesses (mmio/RAM). Remapped regions - In the x86_32 arch, the lower 12MB are being remapped, and the picture of the lower 12MB in e820 is kept for nativedom_e820 (if, for instance there is a reserved areas somewhere in the range of 0-12MB it will be kept. In the x86_32 it is a bit simpler, but there are still memory remapping (for the 512KB-1MB region), so the remapped region destination should not be accessed from NativeDom and it should be marked as reserved in nativedom_e820 (If we remap 0.5-1MB to 16-16.5MB, then the 16-16.5MB *gfns* should be protected and not be populated to NativeDom). You'll also have to perform "smart" e820 manipulations for a >4GB NativeDom (when it'll be supported). Thanks, Guy. > -----Original Message----- > From: Keir Fraser [mailto:Keir.Fraser@xxxxxxxxxxxx] > Sent: Tuesday, September 25, 2007 5:18 PM > To: Guy Zana; xen-devel@xxxxxxxxxxxxxxxxxxx > Subject: Re: [Xen-devel] [NEO 1:1] Nativedom 1:1 Mapping > > On 25/9/07 16:05, "Guy Zana" <guy@xxxxxxxxxxxx> wrote: > > > I sent the patch for review (not for inclusion). > > I know you are not very fond of the E820_1TO1 addition. > > > > You mean it would be cleaner to mark these 1:1 chunks as > reserved? Or > > do you suggest to do that completely differently? > > Can you elaborate on that please? > > Firstly, yes: I would mark the region as reserved or remove > it completely, rather than marking it with a newly-invented > type code. Secondly I would think you only need to modify > boot_e820, probably using the helper function > reserve_in_boot_e820(), because that will suffice to hide the > memory from the normal memory allocator. And that's all > you're trying to do, right? > > -- Keir > > > _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxxxxxxxx http://lists.xensource.com/xen-devel
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