A few questions on the buildroot

Applications, development tools, FPGA, C, WEB
Post Reply
davidbarton
Posts: 3
Joined: Tue Sep 30, 2014 11:35 am

A few questions on the buildroot

Post by davidbarton » Fri Oct 10, 2014 10:43 am

Hi,

I've been looking through the buildroot and related components and I have a few questions:

1) The buildroot config (in OS/buildroot/config) seems to suggest that the CPU is big endian - however the Xilinx website seems to indicate that it is little endian. Which is it?

2) Throughout the soft float calling convention is used; is there any reason for this? Will things break if I change it to hard float?

3) Is there any way to set the u-boot bootargs without having to rebuild everything?

Thanks!
David

Nils Roos
Posts: 1441
Joined: Sat Jun 07, 2014 12:49 pm
Location: Königswinter

Re: A few questions on the buildroot

Post by Nils Roos » Fri Oct 10, 2014 3:23 pm

Hi,
3) Is there any way to set the u-boot bootargs without having to rebuild everything?
If you just want to change the uboot bootargs, you only need to build the "build/boot.bin" target. You can fastpath the build even further by using a pre-compiled fpga bitstream and hardware information. To do that you could change the FPGA/Makefile something like

Code: Select all

$(FPGA_BIT):
ifdef FPGA_PREBUILT
        mkdir --parents $(SDK_EXPORT)/hw
        cp $(FPGA_PREBUILT)/ps7_init.* $(SDK_EXPORT)/hw/
        cp $(FPGA_PREBUILT)/system.xml $(SDK_EXPORT)/hw/
        mkdir --parents $(FPGA_DIR)/$(FPGA_TOOL)/red_pitaya.runs/impl_1
        cp $(FPGA_PREBUILT)/red_pitaya_top.bit $(FPGA_DIR)/$(FPGA_TOOL)/red_pitaya.runs/impl_1/
else
        make -C $(FPGA_DIR) FPGA_TOOL=$(FPGA_TOOL) fpga
endif
(just copy the ps7_init.*, system.xml and red_pitaya_top.bit from a succesful build to a directory outside the RP directory and "export FPGA_PREBUILT=<dir>" before calling "make build/boot.bin" the next time)
(Oh, and the indented Makefile lines need to be [TAB]ed, but this comment editor does not want to do that)

davidbarton
Posts: 3
Joined: Tue Sep 30, 2014 11:35 am

Re: A few questions on the buildroot

Post by davidbarton » Tue Oct 14, 2014 2:04 pm

Thanks very much for the pointers.

For future reference, it actually turns out that the bootargs in u-boot get ignored/overwritten by defaults set in the devicetree.dtb file. Thankfully it's much easier to edit this file (convert it back to a text-based dts file with the dtc utility and back again) than regenerating the boot.bin file!

Post Reply
jadalnie klasyczne ekskluzywne meble wypoczynkowe do salonu ekskluzywne meble tapicerowane ekskluzywne meble do sypialni ekskluzywne meble włoskie

Who is online

Users browsing this forum: Google [Bot] and 17 guests