From: Alistair Francis <alistair23@gmail.com>
To: "Alex Bennée" <alex.bennee@linaro.org>
Cc: "Peter Maydell" <peter.maydell@linaro.org>,
"Thomas Huth" <thuth@redhat.com>,
"Daniel P. Berrangé" <berrange@redhat.com>,
"Richard Henderson" <richard.henderson@linaro.org>,
"QEMU Developers" <qemu-devel@nongnu.org>,
qemu-discuss <qemu-discuss@nongnu.org>,
"Christian Borntraeger" <borntraeger@de.ibm.com>,
qemu-s390x <qemu-s390x@nongnu.org>,
qemu-arm <qemu-arm@nongnu.org>,
"open list:New World" <qemu-ppc@nongnu.org>,
"open list:RISC-V" <qemu-riscv@nongnu.org>
Subject: Re: [RFC PATCH] configure: deprecate 32 bit build hosts
Date: Thu, 26 Sep 2019 09:11:17 -0700 [thread overview]
Message-ID: <CAKmqyKOSyhd5zv0hOa_THCX8g1fxN69NXWxCw0m+=TA+8h0Wug@mail.gmail.com> (raw)
In-Reply-To: <87d0fn9ix8.fsf@linaro.org>
On Thu, Sep 26, 2019 at 8:41 AM Alex Bennée <alex.bennee@linaro.org> wrote:
>
>
> Thomas Huth <thuth@redhat.com> writes:
>
> > On 26/09/2019 15.46, Christian Borntraeger wrote:
> >>
> >>
> >> On 26.09.19 14:58, Daniel P. Berrangé wrote:
> >>> On Thu, Sep 26, 2019 at 08:50:36AM +0100, Peter Maydell wrote:
> >>>> On Thu, 26 Sep 2019 at 00:31, Alex Bennée <alex.bennee@linaro.org> wrote:
> >>>>>
> >>>>> The 32 bit hosts are already a second class citizen especially with
> >>>>> support for running 64 bit guests under TCG. We are also limited by
> >>>>> testing as actual working 32 bit machines are getting quite rare in
> >>>>> developers personal menageries. For TCG supporting newer types like
> >>>>> Int128 is a lot harder with 32 bit calling conventions compared to
> >>>>> their larger bit sized cousins. Fundamentally address space is the
> >>>>> most useful thing for the translator to have even for a 32 bit guest a
> >>>>> 32 bit host is quite constrained.
> >>>>>
> >>>>> As far as I'm aware 32 bit KVM users are even less numerous. Even
> >>>>> ILP32 doesn't make much sense given the address space QEMU needs to
> >>>>> manage.
> >>>>
> >>>> For KVM we should wait until the kernel chooses to drop support,
> >>>> I think.
> >>>
> >>> What if the kernel is waiting for QEMU to drop support too ;-P
> >>
> >> For what its worth on kvm/s390 we never cared about implementing
> >> 32 bit.
> >
> > Looking at tcg/s390/tcg-target.inc.c :
> >
> > ...
> > /* We only support generating code for 64-bit mode. */
> > #if TCG_TARGET_REG_BITS != 64
> > #error "unsupported code generation mode"
> > #endif
> > ...
> >
> > ... it seems to me that TCG does not support 32-bit on s390 either. I
> > think we can remove s390 (32-bit) from the list completely?
>
> It's the same for riscv32 I think.
I think riscv32 host *should* work, although I don't think it was ever tested.
Considering that we have enough trouble keeping the riscv32 kernel
booting it's probably ok to drop it from QEMU.
Alistair
>
> >
> > Thomas
>
>
> --
> Alex Bennée
>
next prev parent reply other threads:[~2019-09-26 16:31 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-09-25 23:30 [RFC PATCH] configure: deprecate 32 bit build hosts Alex Bennée
2019-09-26 7:29 ` Philippe Mathieu-Daudé
2019-09-26 7:50 ` Peter Maydell
2019-09-26 12:58 ` Daniel P. Berrangé
2019-09-26 13:46 ` Christian Borntraeger
2019-09-26 14:26 ` Thomas Huth
2019-09-26 15:27 ` Alex Bennée
2019-09-26 16:11 ` Alistair Francis [this message]
2019-09-26 19:02 ` Alex Bennée
2019-09-27 8:55 ` Gerd Hoffmann
2019-09-26 15:31 ` Alex Bennée
2019-09-26 17:11 ` Richard Henderson
2019-09-30 9:25 ` Daniel P. Berrangé
[not found] ` <87impakrky.fsf@linaro.org>
2019-09-30 10:36 ` Peter Maydell
2019-09-30 11:41 ` Peter Maydell
2019-10-01 17:56 ` Mark Cave-Ayland
2019-10-01 18:02 ` Richard Henderson
2019-10-02 9:10 ` Daniel P. Berrangé
2019-10-02 15:16 ` Richard Henderson
2019-09-26 7:55 ` Thomas Huth
2019-09-26 15:27 ` Alex Bennée
2019-09-27 10:42 ` Mark Cave-Ayland
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