On Thursday 23 December 2010 11:10:37 Wolfgang Denk wrote: > Dear Michael Schwingen, > > In message <[email protected]> you wrote: > > Startup code. Is the following correct? > > > > - code starts from flash, with TEXT_BASE = start of flash, ie. the code > > > > is linked to flash addresses. > > Correct. > > > - DATA/BSS are behind the text segment in flash, so the code may not > > > > write RAM variables until relocation > > Correct. > > In addition, BSS is not initialized yet, so you should not even try > reading variables in BSS, as these will contain random data. This > affects especially static variables that are supposed to be > initialized with zero. > > > - code in flash sets up RAM, copies + relocates u-boot to RAM, and > > > > continues there > > Correct. > > > Timer system. > > > > - For IXP, there are two variants of the timer system - one using > > > > interrupts, and one without interrupts. Both do not work currently. > > I have patches that fix the non-interrupt version, changing > > CONFIG_SYS_HZ from 66666666 to 1000, bringing it in line with what most > > other ARM platforms do. > > I cannot nomment on this. Marek?
http://download.intel.com/design/network/manuals/25248006.pdf page 411 or so. What's the second variant ? Either way -- you should use the non-interrupt version. Remember, you're writing a bootloader, use the KISS principle ; you generally use the timer only to implement *delay() functions. Therefore, as Wolfgang said, you use 1000 ticks per second in uboot's internal counting, but "convert" it from/to your real timer's ticks in timer.c What problem do you have there? Also, can you please let us see the patches? > > > What is the preferred way of handling timers? Should CONFIG_SYS_HZ be > > 1000 or rather the timer clock? > > CONFIG_SYS_HZ must always be defiend as 1000. > > > What about interrupts? Use them or avoid them? > > If you can do without interrupts, I would do that, because it's > simpler. > > > What about the Intel reference board (IXDP425)? Previously, I used that > > one as a reference on how things should be done, but it looks broken, > > too. I can prepare patches for IXDP425, but I can't currently test them > > (we should have one at work, but that might take some time). > > I cannot help with that either. Marek? Go ahead, patches are welcome. I don't have any ixp hardware, but it looks fairy similar to pxa, it should be easy to review patches. > > Best regards, > > Wolfgang Denk Cheers _______________________________________________ U-Boot mailing list [email protected] http://lists.denx.de/mailman/listinfo/u-boot
