[cc'ing the boot architecture list; this conversation should be in public]

On Wed, May 29, 2013 at 11:19 AM, Leif Lindholm leif.lindholm@linaro.org wrote:

Hi Yi,

On 28 May 2013 15:52, Li Yi yi.li@linaro.org wrote:

...

just modify linux loader , add SMBIOS address information into fdt. then

I will modify the dmidecode to parse the /dev/devicetree to find SMBIOS table pointer. Maybe this way can skip grub and kernel's modification.

Ok, yes, that should work.

...

the only problem I care about is the address wrote into fdt ,it is a

real physical address, does dmidecode (tool) can read this address ,and do the right thing? it need to be proved.

Yes - UEFI is guaranteed to run with a 1:1 mapping, so the address you see it at in the UEFI linux loader is the physical address.

...

Grant: if kernel will use the SMBIOS's region memory, can I reserve the

64M memory from the top total ,then kernel will know it's reserved ,will not use the region again ,right?

That should be enough.

Yes, but you shouldn't even need to do that. I just looked at the LinuxLoader code, in particular the UEFI FDT code, and I've noticed that the reserved regions should already be set up. Look in ArmPkg/Library/BdsLib/BdsLinuxFdt.c, about line 420. The function PrepareFdt() retrieves the UEFI memory map and calls fdt_add_mem_rsv() for each region.

It does use the function IsLinuxReservedRegion() to filter the regions, so if SMBIOS uses a different region type then you'll need to add that type to the list.

So, if I'm correct, it should be sufficient to merely enable SMBIOS support in UEFI and the kernel will automatically mark the SMBIOS region as reserved. You can verify this by adding "memblock=debug" to the kernel command line and looking at the kernel boot output. You'll see something like this:

memblock_reserve: [0x00000000008400-0x0000000042e98c] arm_memblock_init+0x4c/0x150 memblock_reserve: [0x00000004000000-0x0000000452f400] arm_memblock_init+0xcc/0x150 memblock_reserve: [0x00000000004000-0x00000000008000] arm_memblock_init+0xf0/0x150 memblock_reserve: [0x00000004530000-0x00000004537350] arm_dt_memblock_reserve+0x30/0xb0 MEMBLOCK configuration: memory size = 0x8000000 reserved size = 0x960cdc memory.cnt = 0x1 memory[0x0] [0x00000000000000-0x00000007ffffff], 0x8000000 bytes reserved.cnt = 0x4 reserved[0x0] [0x00000000004000-0x00000000007fff], 0x4000 bytes reserved[0x1] [0x00000000008400-0x0000000042e98b], 0x42658c bytes reserved[0x2] [0x00000004000000-0x0000000452f3ff], 0x52f400 bytes reserved[0x3] [0x00000004530000-0x0000000453734f], 0x7350 bytes Memory policy: ECC disabled, Data cache writeback memblock_reserve: [0x00000007fff000-0x00000008000000] memblock_alloc_base_nid+0x68/0x84 memblock_reserve: [0x00000007ffe000-0x00000007fff000] memblock_alloc_base_nid+0x68/0x84 memblock_reserve: [0x00000007ffdf10-0x00000007ffe000] memblock_alloc_base_nid+0x68/0x84 memblock_reserve: [0x00000007ffc000-0x00000007ffd000] memblock_alloc_base_nid+0x68/0x84 memblock_reserve: [0x00000007ffb000-0x00000007ffc000] memblock_alloc_base_nid+0x68/0x84 memblock_reserve: [0x00000007ffa000-0x00000007ffb000] memblock_alloc_base_nid+0x68/0x84

Note: this only works with the UEFI LinuxLoader. The GRUB code doesn't currently add the UEFI reserved regions to the FDT reserved map.

g.