Re: [PATCH v1 1/4] s390x: saving regs for interrupts

Pierre Morel
2019-11-14T10:11:54Z

On 2019-11-13 17:12, Janosch Frank wrote:
> On 11/13/19 1:23 PM, Pierre Morel wrote:
>> If we use multiple source of interrupts, for exemple, using SCLP console
>> to print information while using I/O interrupts or during exceptions, we
>> need to have a re-entrant register saving interruption handling.
>>
>> Instead of saving at a static place, let's save the base registers on
>> the stack.
>>
>> Note that we keep the static register saving that we need for the RESET
>> tests.
>>
>> We also care to give the handlers a pointer to the save registers in
>> case the handler needs it (fixup_pgm_int needs the old psw address).
> So you're still ignoring the FPRs...
> I disassembled a test and looked at all stds and it looks like printf
> and related functions use them. Wouldn't we overwrite test FPRs if
> printing in a handler?

If printf uses the FPRs in my opinion we should modify the compilation
options for the library.

What is the reason for printf and related functions to use floating point?

I will have a deeper look at this.

Regards,

Pierre

--
Pierre Morel
IBM Lab Boeblingen