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writing bootloader for FPGA processor
Posted: Tue May 20, 2008 12:40 am
by ravi_chobey
Hi All,
Can some body give an idea to write a bootloader for Xilinx FPGA based processor?
Regards,
Ravi
Posted: Tue May 20, 2008 1:42 am
by JamesM
Hi,
The wiki page for Xilinx says that they mainly configure their FPGAs as systems on a chip with (up to 2) PowerPC cores.
PowerPC cores in non embedded systems tend to be booted by OpenFirmware (or another OpenBIOS compliant loader), and from there booting an OS is easy (OpenFirmware provides filesystem support so it can just load an ELF from disk and execute).
However as your chip is embedded, OpenFirmware possibly won't be available, owing to the fact that it is
massive. In which case your best bet is to read the
PowerPC manual to find out where it starts on bootup, and what is required to boot it. This will involve poking binaries into the ROM or flash from which it boots - but with an embedded device I suppose you were expecting to do that anyway!
Cheers,
James
Posted: Tue May 20, 2008 5:08 am
by grover
The PowerPC boots as usual by jumping to its reset vector (not sure which address right now, I'm at home and don't have my virtex dev board next to me.)
Ussually you initialize the FPGA (Virtex-4 in my case) by programming it with a bitstream from an external processor or SystemACE or System Flash. The FPGA contains a BRAM, which is mapped into the address space of the Power PC and also contains the jump for the reset vector. This is all programmed in one step if I recall correctly. From there on you have code running on the PowerPC and can do anything you like, like loading your operating system or embedded software from flash into SRAM/SDRAM and run it from there.