On 08/24/16 at 11:25am, James Morse wrote:
> Hi Dave,
>
> On 24/08/16 09:04, Dave Young wrote:
> > Looking the arm-init.c, I suspect it missed the some efi ranges as
> > reserved ranges like runtime code and runtime data etc. But I might be
> > wrong.
>
> This had me confused for too... I think I get it, my understanding is:
>
James, thanks for your clarification.
>
> > static __init int is_reserve_region(efi_memory_desc_t *md)
> > {
> > switch (md->type) {
> > case EFI_LOADER_CODE:
> > case EFI_LOADER_DATA:
> > case EFI_BOOT_SERVICES_CODE:
> > case EFI_BOOT_SERVICES_DATA:
> > case EFI_CONVENTIONAL_MEMORY:
> > case EFI_PERSISTENT_MEMORY:
> > return 0;
>
> return false - this is the list of region-types to never reserve, regardless of
> memory attributes.
>
>
> > default:
> > break;
> > }
> > return is_normal_ram(md);
>
> If its not in the 'never reserve' list above, then we check if the region is
> 'normal' ram. If it is then it will end up in memblock.memory so we return true,
> causing it to be marked nomap too.
>
> reserve_regions() in that same file calls is_normal_ram() directly before adding
> all regions with the WB attribute to memblock.memory via
> early_init_dt_add_memory_arch().
>
> A runtime region with the WB attribute will be caught by is_reserve_region(),
> and is_normal_ram(), so it ends up in memblock.memory and memblock.nomap.
Hmm, It is not straitforward like the do_add_efi_memmap. I got it.
BTW, I believe there is same problem in arm as well as arm64, it also
need mark the runtime ranges as "reserved" /proc/iomem.
>
>
> > }
> >
> > Let's see the x86 do_add_efi_mem_map, the default case set all other
> > types as reserved. Shouldn't this be same in all arches though there's
> > no e820 in arm(64)?
>
> > static void __init do_add_efi_memmap(void)
> > {
> >
> > [snip]
> > switch (md->type) {
> > case EFI_LOADER_CODE:
> > case EFI_LOADER_DATA:
> > case EFI_BOOT_SERVICES_CODE:
> > case EFI_BOOT_SERVICES_DATA:
> > case EFI_CONVENTIONAL_MEMORY:
> > if (md->attribute & EFI_MEMORY_WB)
> > e820_type = E820_RAM;
>
> In this case reserve_regions() will add the memory to memblock.memory because it
> has the WB attribute, and not reserve it.
>
>
> > else
> > e820_type = E820_RESERVED;
>
> Without the WB attribute, these regions are in neither memblock.memory nor
> memblock.nomap.
>
>
> > break;
> > [snip]
> > default:
> > /*
> > * EFI_RESERVED_TYPE EFI_RUNTIME_SERVICES_CODE
> > * EFI_RUNTIME_SERVICES_DATA
> > * EFI_MEMORY_MAPPED_IO
> > * EFI_MEMORY_MAPPED_IO_PORT_SPACE EFI_PAL_CODE
> > */
> > e820_type = E820_RESERVED;
> > break;
>
> If any other regions has the WB attribute, it will be added to memblock.memory
> and memblock.nomap. If it doesn't, it will appear in neither.
>
>
> > }
> > [snip]
> > }
>
> Does this help at all?
>
Yes, thanks a lot!
Dave
>
> Thanks,
>
> James
