[U-Boot] Galileo instructions

[Bin Meng]

Hi Simon,

On Mon, Sep 14, 2015 at 8:51 PM, Simon Glass <sjg at chromium.org> wrote:
> Hi Bin,
>
> On 14 September 2015 at 06:49, Bin Meng <bmeng.cn at gmail.com> wrote:
>>
>> Hi Simon,
>>
>> On Mon, Sep 14, 2015 at 8:45 PM, Simon Glass <sjg at chromium.org> wrote:
>> > Hi Bin,
>> >
>> > On 13 September 2015 at 03:28, Bin Meng <bmeng.cn at gmail.com> wrote:
>> >> Hi Simon,
>> >>
>> >> On Sun, Sep 13, 2015 at 5:06 AM, Simon Glass <sjg at chromium.org> wrote:
>> >>> Hi Bin,
>> >>>
>> >>> I have a Galileo Gen 2 and am trying to get U-Boot to start on it. The
>> >>> first problem I have is that the schematic says the chip is a W25Q64FV
>> >>> which I think is an 8MB part, but the image produced is only 1MB.
>> >>
>> >> Yes, the board has an 8MB SPI flash, but U-Boot (u-boot.rom) only
>> >> utilizes the last 1MB.
>> >>
>> >>>
>> >>> Also I know that there is a Gen 1 and a Gen 2. I recall you saying
>> >>> that U-Boot supports the Gen 2 but can easily support the Gen 1. But
>> >>> perhaps I have done something wrong.
>> >>>
>> >>
>> >> I've verified U-Boot can boot on both gen1 and gen2 boards.
>> >
>> > Thanks.
>> >>
>> >>> I downloaded the BSP from here:
>> >>>
>> >>> https://downloadcenter.intel.com/download/23197/Intel-Quark-BSP
>> >>>
>> >>> File name: Board_Support_Package_Sources_for_Intel_Quark_v1.1.0.7z
>> >>> Version: 1.1.0 (Latest)
>> >>>
>> >>> Date: 03/03/2015
>> >>> Size: 2.72 MB
>> >>>
>> >>> Any hints? I am using a dediprog em100 with a test clip over the flash chip.
>> >>>
>> >>
>> >> It's not clear to me what issue you got. It looks like there might be
>> >> some issue for dediporg em100 to handle the rom size mismatch? If this
>> >> is the case, you can just create an 8MB u-boot.rom with the 1MB
>> >> version with other 7MB filled up with 0xFFs.
>> >
>> > OK I did this and it works, thanks.
>>
>> So it's indeed the dediprog em100 cannot handle the rom mismatch?
>>
>> > Why don't we just change the ROM size? This point is not mentioned in README.x86.
>> >
>>
>> 1MB is enough for U-Boot. u-boot.rom does not necessarily have to
>> match the SPI flash size. And on Galileo since there is no Intel ME,
>> so we don't need to create a whole 8MB rom. This is the same as Intel
>> CrownBay, which has a 2MB SPI flash, but still 1MB u-boot.rom.
>
> What is the benefit of this mismatch? I only see the down-side at
> present (user confusion, unbootable .rom).

I don't see this as a down-side. Why did you call this as unbootable
.rom? The Dediprog em100 does not work does not mean it is not
bootable. The assumption is to program this 1MB u-boot.rom to the last
1MB of the SPI flash. Perhaps you need contact Dediprog to fix their
em100 tool to handle such rom mismatch correctly. Or maybe there is
some parameter to control such behavior that you are not aware of. I
think this is quite a normal use case, as is exactly the same as other
architectures, that u-boot.bin does not have to match the flash media
size. Say on PowerPC BookE processors, the NOR flash media can be 8MB,
16MB, but the generated bootable u-boot.bin is 512KB, 1MB, etc (Check
these Freescale QorIQ boards in U-Boot). Users need program u-boot.bin
to the last 512KB or 1MB in the NOR flash.

And I don't see this is a confusion. Perhaps all x86 boards you've
played before require the Intel ME firmware, in which case your
u-boot.rom MUST match the SPI flash size, but we have to realize Intel
ME is an optional feature and not every x86 board requires that. I am
afraid this is a preconceived idea instead of confusion.

Regards,
Bin