Booting without Uboot on 8548E
Benjamin Herrenschmidt
benh at kernel.crashing.org
Sat Nov 4 20:13:40 EST 2006
On Sat, 2006-11-04 at 08:52 +0000, M Ptich wrote:
> Documentation mentions that the only dependencies between 2.6 Kernel and
> bootloader are:
>
> 1. 5 input parameters (bd_t pointer, start and end of command line, start
> and end of ram disk)
> 2. bd_t pointer and command line must with within 16MB of Kernel
> 3. Initial TLB1 entry must have IPROT=1
This is for arch/ppc, which is sort-of deprecated. You should seriously
think about porting over to arch/powerpc instead.
> Slowly, we are finding that this list is not complete. For example, address
> calculation at the start of platform_init (r3 + ...) assumes that Kernel has
> been initially loaded at 0-base virtual address.
For which CPU core ? 6xx/7xx/7xxx/G2 cores don't assume such a thing,
the kernel can be loaded anywhere as long as the virtual and physical
addresses are the same.
> And now we are stuck with apparently another dependency: our Kernel fails to
> advance beyond time calibration because jiffies are not getting incremented,
> so we are not getting timer interrupts. Is it true that Kernel relies on
> EPIC timer set in Uboot ? If not - where the timer insterrupts are
> configured ?
I'm not familiar about which core family the 85xx is. Doesn't it use the
decrementer ?
Ben.
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