Messages in this thread | | | Date | Sat, 19 Jan 2008 16:46:51 +0100 | From | Andi Kleen <> | Subject | Re: ACPI early ioremap problems |
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On Sat, Jan 19, 2008 at 04:30:55PM +0100, Ingo Molnar wrote: > > > that case it's a 64-bit early_ioremap() bug that we want to find > > > even if ACPI didnt use early_ioremap(). > > > > > > and this all runs before zap_low_mappings(), right? > > > > No after. Since some time x86-64 does the equivalent of z_l_m() in > > head64(); this means before start_kernel and definitely before > > setup_arch which sets up ACPI. > > that would mean early_ioremap() should switch to ioremap() after that > point. Could you try that, does it resolve the failure you are seeing?
ioremap() does alloc_page and that won't work before paging_init(). Early ACPI scan is before paging_init() because paging_init() needs node discovery at at least; which requires some ACPI tables.
> Long-term we want to have a single, uniform ioremap() interface (on > 32-bit and 64-bit x86 as well) that can be used anytime, which just > switches to the right lowlevel method depending on how far we are into > the pagetable and memory subsystem bootstrap - instead of these more > fragile "can we now use early_ioremap() or should we already be using > ioremap()" usages.
I didn't think there were enough early/bt_ioremap() users for this to be really worthwhile. The only code that does both I'm aware of is the memory setup code.
-Andi
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