On 30.09.16 02:03, Stefan Brüns wrote:
Currently each allocation creates a new mapping. Readding the mapping as free memory (EFI_CONVENTIONAL_MEMORY) potentially allows to hand out an existing mapping, thus limiting the number of mapping descriptors in the memory map.
Mitigates a problem with current (4.8rc7) linux kernels when doing an efi_get_memory map, resulting in an infinite loop. Space for the memory map is reserved with allocate_pool (implicitly creating a new mapping) and filled. If there is insufficient slack space (8 entries) in the map, the space is freed and a new round is started, with space for one more entry. As each round increases requirement and allocation by exactly one, there is never enough slack space. (At least 32 entries are allocated, so as long as there are less than 24 entries, there is enough slack). Earlier kernels reserved no slack, and did less allocations, so this problem was not visible.
Signed-off-by: Stefan Brüns stefan.bruens@rwth-aachen.de
Reviewed-by: Alexander Graf agraf@suse.de
Alex