On 12 November 2013 13:29, Albert ARIBAUD <albert.u.b...@aribaud.net> wrote: > Hi Christoffer, > > On Tue, 12 Nov 2013 09:09:23 -0800, Christoffer Dall > <christoffer.d...@linaro.org> wrote: > >> I suspect that if you are in Hyp mode, you should not worry about >> FIQ/IRQ mode, but just make sure to configure Hyp mode properly to >> handle interrupts. (it's a separate entry in the exception vector and >> you probably need to look at the HSR register whn you've taken an >> interrupt). So, as Andre suggests below, it depends on your use case. > > Ok, so les me try to sum that up from my perspective (IRQ and FIQ > stacks in U-Boot): > > Some ARM U-Boot targets run in SVC32 mode, and some in HYP mode. > > For targets which run in SVC32 mode: aborts execute in abort mode, IRQs > in IRQ mode, FIQs in FIQ mode, etc., each mode having its own stack.
correct > > For targets which run in HYP mode: aborts, FIQ and IRQs all run in HYP > mode, using always the same stack. correct. > > In both types of targers: prefetch and data aborts, FIQs and IRQs > execute through the usual vectors; in SVC32 mode, because there's no > other way; in HYP mode, because exceptions occurring while in HYP > mode use the normal vector, not the HYP vector. > > Correct? > no, this sounds fishy. Look at the ARM ARMv7 (DDI 0406C.b) page B1-1166. Table B1-3 will tell you what you need to know. Hyp mode has its own vectors, pointed to by the HVBAR control register. I strongly suggest you familiarize yourself with these parts of the ARM ARM before writing code to that effect. > If so, then U-Boot stack requirements for SVC32 and HYP mode are > as follows: in SVC32, we need separate IRQ and FIQ stacks, and the main > (SVC32) stack does not have to accommodate for interrupt handler > context storage. In HYP mode, the only stack is the HYP one and > exception handlers will use it too, so it has to accommodate for > their context storage. > That is correct, your Hyp mode stack should always be valid (have a page or so, like the kernel) and then you can always push things on there, even when taking an exception. -Christoffer _______________________________________________ U-Boot mailing list U-Boot@lists.denx.de http://lists.denx.de/mailman/listinfo/u-boot
