From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx0a-001b2d01.pphosted.com ([148.163.156.1]:47074 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726115AbfKNL5r (ORCPT ); Thu, 14 Nov 2019 06:57:47 -0500 Received: from pps.filterd (m0098410.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.16.0.27/8.16.0.27) with SMTP id xAEBv6IL046311 for ; Thu, 14 Nov 2019 06:57:46 -0500 Received: from e06smtp02.uk.ibm.com (e06smtp02.uk.ibm.com [195.75.94.98]) by mx0a-001b2d01.pphosted.com with ESMTP id 2w94yk46vj-1 (version=TLSv1.2 cipher=AES256-GCM-SHA384 bits=256 verify=NOT) for ; Thu, 14 Nov 2019 06:57:45 -0500 Received: from localhost by e06smtp02.uk.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Thu, 14 Nov 2019 11:57:43 -0000 Subject: Re: [PATCH v1 1/4] s390x: saving regs for interrupts References: From: Pierre Morel Date: Thu, 14 Nov 2019 12:57:40 +0100 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset="utf-8"; format="flowed" Content-Transfer-Encoding: 8bit Content-Language: en-US Message-Id: Sender: linux-s390-owner@vger.kernel.org List-ID: To: David Hildenbrand Cc: Janosch Frank , kvm@vger.kernel.org, linux-s390@vger.kernel.org, thuth@redhat.com On 2019-11-14 11:28, David Hildenbrand wrote: > >> Am 14.11.2019 um 11:11 schrieb Pierre Morel : >> >>  >>> 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? >> > Register spilling. This can and will be done. Hum, can you please clarify? AFAIK register spilling is for a compiler, to use memory if it has not enough registers. So your answer is for the my first sentence, meaning yes register spilling will be done or do you mean register spilling is the reason why the compiler use FPRs and it must be done so? Thanks, Pierre > > Cheers. > >> I will have a deeper look at this. >> >> >> Regards, >> >> Pierre >> >> >> -- >> Pierre Morel >> IBM Lab Boeblingen >> -- Pierre Morel IBM Lab Boeblingen