On Fri, 04 Aug, at 07:40:05PM, Baoquan He wrote: > On 08/04/17 at 12:23pm, Matt Fleming wrote: > > On Fri, 28 Jul, at 07:26:03PM, Baoquan He wrote: > > > Hi Matt, > > > > > > On 07/28/17 at 11:55am, Ingo Molnar wrote: > > > > > > > > * Matt Fleming <matt@xxxxxxxxxxxxxxxxxxx> wrote: > > > > > > > > > On Fri, 21 Jul, at 09:19:56PM, Baoquan He wrote: > > > > > > > > > > > > There are places where the efi map is getting and used like this. E.g > > > > > > in efi_high_alloc() of drivers/firmware/efi/libstub/efi-stub-helper.c. > > > > > > EFI developers worry the size of efi_memory_desc_t could not be the same > > > > > > as e->efi_memdesc_size? > > > > > > > > > > > > Hi Matt, > > > > > > > > > > > > Could you help have a look at this? > > > > > > > > > > You're exactly right. The code guards against the size of the > > > > > efi_memory_desc_t struct changing. The UEFI spec says to traverse the > > > > > memory map this way. > > > > > > > > This is not obvious and looks pretty ugly as well, and open coded in several > > > > places. > > > > > > > > At minimum we should have an efi_memdesc_ptr(efi, i) wrapper inline (or so) that > > > > gives us the entry pointer, plus a comment that points out that ->memdesc_size > > > > might not be equal to sizeof(efi_memory_memdesc_t). > > > > > > I can make a efi_memdesc_ptr(efi, i) wrapper as Ingo suggested and use > > > it here if you agree. Seems it might be not good to add another > > > for_each_efi_memory_desc_xxxx wrapper since there are different memmap > > > data structures in x86 boot and in general efi libstub. Or any other > > > idea? > > > > I think adding a wrapper is fine, but I'd suggest including the word > > "early" (or something similar) to explain that it should only be used > > during bootup -- we want everyone else to use the > > for_each_efi_memory_*() API. > > Thanks, Matt. I can do that. Do you think below helper definition is OK > to you? If yes, I can upstate with it and post v9. > > #define efi_early_memdesc_ptr(map, desc_size, n) \ > (efi_memory_desc_t *)((void *)(map) + ((n) * (desc_size))) Looks fine to me, but I'd wait for Ingo's OK before resending. -- To unsubscribe from this list: send the line "unsubscribe linux-efi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
