[U-Boot] [PATCH 1/6] x86: Support machines with >4GB of RAM

[Simon Glass]

Hi Bin,

On 25 February 2015 at 00:10, Bin Meng <bmeng.cn at gmail.com> wrote:
> Hi Simon,
>
> On Wed, Feb 11, 2015 at 9:59 AM, Simon Glass <sjg at chromium.org> wrote:
>> Some systems have more than 4GB of RAM. U-Boot can only place things below
>> 4GB so any memory above that should not be used. Ignore any such memory so
>> that the memory size will not exceed the maximum.
>>
>> This prevents gd->ram_size exceeding 4GB which causes problems for PCI
>> devices which use DMA.
>>
>> Signed-off-by: Simon Glass <sjg at chromium.org>
>> ---
>>
>>  arch/x86/cpu/coreboot/sdram.c | 6 ++++--
>>  1 file changed, 4 insertions(+), 2 deletions(-)
>>
>> diff --git a/arch/x86/cpu/coreboot/sdram.c b/arch/x86/cpu/coreboot/sdram.c
>> index e98a230..9c3ab81 100644
>> --- a/arch/x86/cpu/coreboot/sdram.c
>> +++ b/arch/x86/cpu/coreboot/sdram.c
>> @@ -90,7 +90,8 @@ int dram_init(void)
>>                 struct memrange *memrange = &lib_sysinfo.memrange[i];
>>                 unsigned long long end = memrange->base + memrange->size;
>>
>> -               if (memrange->type == CB_MEM_RAM && end > ram_size)
>> +               if (memrange->type == CB_MEM_RAM && end > ram_size &&
>> +                   memrange->base < (1ULL << 32))
>
> Can we safely assume no single entry in memrange[] lies across the 4GB boundary?

>From what I have seen, yes. There always seems to be a hole in memory
from about 3.3GB to 4GB.

>
>>                         ram_size = end;
>>         }
>>         gd->ram_size = ram_size;
>> @@ -108,7 +109,8 @@ void dram_init_banksize(void)
>>                 for (i = 0, j = 0; i < lib_sysinfo.n_memranges; i++) {
>>                         struct memrange *memrange = &lib_sysinfo.memrange[i];
>>
>> -                       if (memrange->type == CB_MEM_RAM) {
>> +                       if (memrange->type == CB_MEM_RAM &&
>> +                           memrange->base < (1ULL << 32)) {
>>                                 gd->bd->bi_dram[j].start = memrange->base;
>>                                 gd->bd->bi_dram[j].size = memrange->size;
>>                                 j++;
>> --
>
> Regards,
> Bin

Regards,
Simon