>>> On 13.03.18 at 17:20, <maran.wil...@oracle.com> wrote: > On 3/13/2018 3:50 AM, Roger Pau Monné wrote: >> On Fri, Mar 02, 2018 at 12:54:29PM -0800, Maran Wilson wrote: >>> @@ -62,10 +72,34 @@ >>> * | reserved | >>> * 32 +----------------+ >>> * >>> + * The layout of each entry in the memory map table is as follows: >>> + * >>> + * 0 +----------------+ >>> + * | addr | Base address >>> + * 8 +----------------+ >>> + * | size | Size of mapping in bytes >>> + * 16 +----------------+ >>> + * | type | Type of mapping as defined between the hypervisor >>> + * | | and guest it's starting. E820_TYPE_xxx, for >>> example. >> This needs a link to the expected type values (or a reference). Or you >> need to spell out the relation between the values and the memory types. > > This field was discussed a good deal in v2 of the linux patches. I had > originally defined this to be a specific type field, matching the > x86/Linux definition for e820 memory mapping types. But Jan Beulich > successfully argued that we should keep the definition of this > particular interface agnostic to architecture and OS and not limit the > field to specific values. I believe the central idea behind Jan's > argument was to keep the interface x86-agnostic as well as preserving > the option to add additional memory mapping types in the future without > them being sanctioned by whoever maintains E820 type assignments. > > That's why I changed the comment wording to what it is now. Basically > spelling out the fact that this field simply needs to be agreed upon > between the producer and the consumer since a hypervisor should > generally know what type of guest it is starting. And I mentioned > e820_type_xxx as the *example* of one such implementation, since that is > the most obvious use case and the e820 types are part of the ACPI > standard (and thus easy to find/reference).
But Roger makes a valid remark here. Statements like "E820_TYPE_xxx, for example" are simply to vague for a stable public interface. Jan _______________________________________________ Xen-devel mailing list Xenemail@example.com https://lists.xenproject.org/mailman/listinfo/xen-devel