On 01.02.2012, at 14:52, Anthony Liguori wrote:
Fine, but to boot u-boot, the real hardware must set IP to something that's
most likely an offset into ROM flash.
Why can't we bootstrap semi-hosted mode by having a ROM somewhere that just
redirects IP?
It doesn't have to be a full blown u-boot.
That would work, yes.
That's why I'm saying things don't work out all that simple with semi-hosted
environments. Now you could argue that semi-hosting is a bad thing, but we'll
always have to have it. On s390 for example, semi-hosting is how real hardware
works. Or at least the parts that are visible to end users. Especially when you
model PV machines, you'll have a hard time with fixed reset IPs too.
s390 is a special case because "real hardware" is not actually real hardware.
It's a VM.
Sure, but how would we model things there? Our model needs to be flexible
enough to cope with these oddballs.
In fact, s390 is even more complicated. For DASD boot, the CPU is stalled at
first and instead the DASD controller reads some instructions from memory that
then bootstrap the bootloader. But IIUC that's only the case for DASD boot. For
zfcp boot, you basically get semi-hosting.