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From: Claudio Fontana <cfontana@suse.de>
To: David Hildenbrand <david@redhat.com>,
	Cornelia Huck <cohuck@redhat.com>, Thomas Huth <thuth@redhat.com>,
	Richard Henderson <richard.henderson@linaro.org>
Cc: Halil Pasic <pasic@linux.ibm.com>,
	Christian Borntraeger <borntraeger@de.ibm.com>,
	qemu-s390x@nongnu.org, qemu-devel@nongnu.org,
	Paolo Bonzini <pbonzini@redhat.com>
Subject: Re: [RFC v2 04/13] target/s390x: remove tcg-stub.c
Date: Tue, 20 Apr 2021 15:00:33 +0200
Message-ID: <3f7d3cda-9319-9004-7568-55459bc05c78@suse.de> (raw)
In-Reply-To: <f40727a3-9687-6821-804b-d35fa2bd5d23@redhat.com>

On 4/20/21 2:54 PM, David Hildenbrand wrote:
> On 20.04.21 12:36, Claudio Fontana wrote:
>> now that we protect all calls to the tcg-specific functions
>> with if (tcg_enabled()), we do not need the TCG stub anymore.
> 
> You need compile-time checks, not runtime checks. Any calls have to be 
> protected by #ifdef, otherwise the compiler might bail out.

This is not true though, tcg_enabled() is #defined as 0 if tcg is not enabled.

#define kvm_enabled()           (0)

Compiler will elide the code if after the preprocessor pass the code is:

if (0) {
}

It adds the benefit of actually checking the syntax of the code inside.

As long as the prototypes are in sight, we rely on this for i386 and ARM already, to avoid accumulating stubs.

> 
> Maybe you just wanted to state it differently in this patch description.
> 

Thanks,

Claudio


  reply index

Thread overview: 24+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-04-20 10:36 [RFC v2 00/13] s390x cleanup Claudio Fontana
2021-04-20 10:36 ` [RFC v2 01/13] hw/s390x: only build tod-qemu from the CONFIG_TCG build Claudio Fontana
2021-04-20 12:50   ` David Hildenbrand
2021-04-20 10:36 ` [RFC v2 02/13] hw/s390x: rename tod-qemu.c to tod-tcg.c Claudio Fontana
2021-04-20 12:49   ` David Hildenbrand
2021-04-20 10:36 ` [RFC v2 03/13] hw/s390x: tod: make explicit checks for accelerators when initializing Claudio Fontana
2021-04-20 12:52   ` David Hildenbrand
2021-04-20 10:36 ` [RFC v2 04/13] target/s390x: remove tcg-stub.c Claudio Fontana
2021-04-20 12:54   ` David Hildenbrand
2021-04-20 13:00     ` Claudio Fontana [this message]
2021-04-20 13:04       ` David Hildenbrand
2021-04-20 13:35         ` Claudio Fontana
2021-04-20 13:06   ` David Hildenbrand
2021-04-20 10:36 ` [RFC v2 05/13] target/s390x: start moving TCG-only code to tcg/ Claudio Fontana
2021-04-20 13:16   ` David Hildenbrand
2021-04-20 13:40     ` Claudio Fontana
2021-04-20 10:36 ` [RFC v2 06/13] target/s390x: move sysemu-only code out to cpu-sysemu.c Claudio Fontana
2021-04-20 10:36 ` [RFC v2 07/13] target/s390x: split cpu-dump from helper.c Claudio Fontana
2021-04-20 10:36 ` [RFC v2 08/13] target/s390x: make helper.c sysemu-only Claudio Fontana
2021-04-20 10:36 ` [RFC v2 09/13] target/s390x: use kvm_enabled() to wrap call to kvm_s390_get_hpage_1m Claudio Fontana
2021-04-20 10:36 ` [RFC v2 10/13] target/s390x: remove kvm-stub.c Claudio Fontana
2021-04-20 10:36 ` [RFC v2 11/13] target/s390x: move kvm files into kvm/ Claudio Fontana
2021-04-20 10:36 ` [RFC v2 12/13] target/s390x: split sysemu part of cpu models Claudio Fontana
2021-04-20 10:36 ` [RFC v2 13/13] MAINTAINERS: update s390x directories Claudio Fontana

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