Hi Simon, On Tue, Jan 27, 2015 at 9:23 AM, Simon Glass <s...@chromium.org> wrote: > Some information has been gleaned on tools and procedures for porting > U-Boot to different x86 platforms. Add a few notes to start things off. > > Signed-off-by: Simon Glass <s...@chromium.org> > --- >
Reviewed-by: Bin Meng <bmeng...@gmail.com> A minor comment below. > doc/README.x86 | 63 > ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ > 1 file changed, 63 insertions(+) > > diff --git a/doc/README.x86 b/doc/README.x86 > index 809a291..0e4628a 100644 > --- a/doc/README.x86 > +++ b/doc/README.x86 > @@ -164,6 +164,69 @@ mtrr - List and set the Memory Type Range Registers > (MTRR). These are used to > mode to use. U-Boot sets up some reasonable values but you can > adjust then with this command. > > +Development Flow > +---------------- > + > +These notes are for those who want to port U-Boot to a new x86 platform. > + > +Since x86 CPUs boot from SPI flash, a SPI flash emulator is a good > investment. > +The Dediprog em100 can be used on Linux. The em100 tool is available here: > + > + http://review.coreboot.org/p/em100.git > + > +On Minnowboard Max the following command line can be used: > + > + sudo em100 -s -p LOW -d u-boot.rom -c W25Q64DW -r > + > +A suitable clip for connecting over the SPI flash chip is here: > + > + http://www.dediprog.com/pd/programmer-accessories/EM-TC-8 > + > +This allows you to override the SPI flash contents for development purposes. > +Typically you can write to the em100 in around 1200ms, considerably faster > +than programming the real flash device each time. The only important > +limitation of the em100 is that it only supports SPI bus speeds up to 20MHz. > +This means that images must be set to boot with that speed (Intel-specific > +feature). > + It would be better to document what this Intel-specific feature is in order to support this SPI bus frequency. > +If your chip/board uses an Intel Firmware Support Package (FSP) it is fairly > +easy to fit it in. You can follow the Minnowboard Max implementation, for > +example. Hopefully you will just need to create new files similar to those > +in arch/x86/cpu/baytrail which provide Bay Trail support. > + > +If you are not using an FSP you have more freedom and more responsibility. > +The ivybridge support works this way, although it still uses a ROM for > +graphics and still has binary blobs containing Intel code. You should aim to > +support all important peripherals on your platform including video and > storage. > +Use the device tree for configuration where possible. > + > +For the microcode you can create a suitable device tree file using the > +microcode tool: > + > + ./tools/microcode-tool -d microcode.dat create <model> > + > +or if you only have header files and not the full Intel microcode.dat > database: > + > + ./tools/microcode-tool -H BAY_TRAIL_FSP_KIT/Microcode/M0130673322.h \ > + -H BAY_TRAIL_FSP_KIT/Microcode/M0130679901.h \ > + create all > + > +These are written to arch/x86/dts/microcode/ by default. > + > +Note that it is possible to just add the micrcode for your CPU if you know > its > +model. U-Boot prints this information when it starts > + > + CPU: x86_64, vendor Intel, device 30673h > + > +so here we can use the M0130673322 file. > + > +If you platform can display POST codes on two little 7-segment displays on > +the board, then you can use post_code() calls from C or assembler to monitor > +boot progress. This can be good for debugging. > + > +If not, you can try to get serial working as early as possible. The early > +debug serial port may be useful here. See setup_early_uart() for an example. > + > TODO List > --------- > - Audio > -- Regards, Bin _______________________________________________ U-Boot mailing list U-Boot@lists.denx.de http://lists.denx.de/mailman/listinfo/u-boot