Re: [Qemu-arm] [PATCH 04/18] armv7m: Explicit error for bad vector table

[Peter Maydell]

On 2 December 2015 at 22:55, Michael Davidsaver <address@hidden> wrote:
> On 11/17/2015 12:33 PM, Peter Maydell wrote:
>> The behaviour on a failed vector table read is actually architecturally
>> specified: we should take a nested exception (escalated to HardFault).
>> If it happens while we're trying to take a HardFault in the first place
>> then we go into Lockup (where the CPU sits around repeatedly trying
>> to execute an instruction at 0xFFFFFFFE; it is technically possible
>> to get back out of Lockup by taking an NMI or a system reset).
>>
>> That said, trying to get nested exceptions and priority escalation
>> right is fairly involved, and implementing lockup is both involved
>> and an exercise in pointlessness. So I think this code is an
>> improvement overall.
>
> This is my thinking as well.  One point against it is that abort() is
> inconvenient when using '-gdb'.  I'm not sure if there is something
> else which could be done (cpu halt?).

I can't think of any immediately good suggestions. It is probably
worth at least commenting (a) places where we are not doing the
architectural behaviour (b) places which should go into Lockup.
Then we can find them later if we come up with a better idea...

thanks
-- PMM