[U-Boot] [PATCH 00/82] x86: Add initial support for 64-bit U-Boot

[Simon Glass]

Hi Bin,

On 10 October 2016 at 23:36, Bin Meng <bmeng.cn at gmail.com> wrote:
> Hi Simon,
>
> On Mon, Sep 26, 2016 at 11:33 AM, Simon Glass <sjg at chromium.org> wrote:
>> At present U-Boot runs entirely in 32-bit mode on x86, except for the
>> initial switch from 16-bit mode. On 64-bit machines it is possible to run
>> in 64-bit mode. This series starts the process of adding this support.
>>
>> The main benefit of 64-bit mode for a boot loader is direct access to all
>> available memory. There are also more registers, but this makes very little
>> difference.
>>
>> This feature is implemented by putting all of the 32-bit code in an SPL
>> build. SPL then runs through all the init that has to be done in 32-bit
>> mode, changes to 64-bit mode and then jumps to U-Boot proper.
>>
>> Typically the total code size increases slightly. For example, on link in
>> 32-bit mode, U-Boot has around 480KB of code (admittedly with a large
>> number of features enabled). In 64-bit mode, U-Boot falls to around 460KB,
>> but SPL adds another 60KB, for a net increase of 40KB. Partly this is due
>> to code duplication and partly it is due to the worse code density of
>> 64-bit code on x86.
>>
>> Many major features are not implemented yet, for example:
>> - SDRAM sizing
>> - Booting linux
>> - FSP support
>> - EFI support
>> - SCSI device init
>> - Running video ROMs
>>
>> Still, this is a big step forward towards full 64-bit support. To enable it,
>> select CONFIG_X86_RUN_64BIT.
>>
>> This series is available at u-boot-x86/64-working
>>
>
> Looks it requires a 64-bit toolchain to compile 64-bit U-Boot. For
> example, I used kernel.org i386 toolchain to compile 64-bit U-Boot, I
> got:
>
> include/asm-generic/bitops/__fls.h: In function '__fls':
> include/asm-generic/bitops/__fls.h:17:2: warning: left shift count >=
> width of type
>   if (!(word & (~0ul << 32))) {
>   ^
> include/asm-generic/bitops/__fls.h:19:3: warning: left shift count >=
> width of type
>    word <<= 32;
>    ^
> include/asm-generic/bitops/__fls.h:22:2: warning: left shift count >=
> width of type
>   if (!(word & (~0ul << (BITS_PER_LONG-16)))) {
>   ^
> include/asm-generic/bitops/__fls.h:26:2: warning: left shift count >=
> width of type
>   if (!(word & (~0ul << (BITS_PER_LONG-8)))) {
>   ^
> include/asm-generic/bitops/__fls.h:30:2: warning: left shift count >=
> width of type
>   if (!(word & (~0ul << (BITS_PER_LONG-4)))) {
>   ^
> include/asm-generic/bitops/__fls.h:34:2: warning: left shift count >=
> width of type
>   if (!(word & (~0ul << (BITS_PER_LONG-2)))) {
>   ^
> include/asm-generic/bitops/__fls.h:38:2: warning: left shift count >=
> width of type
>   if (!(word & (~0ul << (BITS_PER_LONG-1))))
>   ^
> arch/x86/cpu/intel_common/microcode.c: In function 'microcode_read_rev':
> arch/x86/cpu/intel_common/microcode.c:79:2: error: PIC register
> clobbered by 'ebx' in 'asm'
>   asm volatile (
>   ^
> make[2]: *** [arch/x86/cpu/intel_common/microcode.o] Error 1

Yes, that is expected.

>
> After I switched to 64-bit toolchain from kernel.org (x86_64-linux),
> there was no such warnings/errors, but I still got build failure at
> last.
>
>   ./tools/binman/binman -d u-boot.dtb -O . -I . -I
> ./board/google/chromebook_link u-boot-x86-16bit.bin
> Traceback (most recent call last):
>   File "./tools/binman/binman", line 31, in <module>
>     import control
>   File "./tools/binman/control.py", line 17, in <module>
>     from image import Image
>   File "./tools/binman/image.py", line 12, in <module>
>     import entry
>   File "./tools/binman/etype/entry.py", line 8, in <module>
>     import importlib
> ImportError: No module named importlib
> make: *** [u-boot.rom] Error 1

What version of python do you use?

Regards,
Simon