Hardly anybody still uses 32-bit x86 hosts today, so we should start deprecating them to stop wasting our time and CI minutes here. For example, there are also still some unresolved problems with these: When emulating 64-bit binaries in user mode, TCG does not honor atomicity for 64-bit accesses, which is "perhaps worse than not working at all" (quoting Richard). Let's simply make it clear that people should use 64-bit x86 hosts nowadays and we do not intend to fix/maintain the old 32-bit stuff. Signed-off-by: Thomas Huth <thuth(a)redhat.com&gt; --- docs/about/deprecated.rst | 12 ++++++++++++ 1 file changed, 12 insertions(+)

diff --git a/docs/about/deprecated.rst b/docs/about/deprecated.rst index 11700adac9..a30aa8dfdf 100644 --- a/docs/about/deprecated.rst +++ b/docs/about/deprecated.rst @@ -208,6 +208,18 @@ CI coverage support may bitrot away before the deprecation process completes. The little endian variants of MIPS (both 32 and 64 bit) are still a supported host architecture. +32-bit x86 hosts (since 8.0) +'''''''''''''''''''''''''''' + +Support for 32-bit x86 host deployments is increasingly uncommon in +mainstream OS distributions given the widespread availability of 64-bit +x86 hardware. The QEMU project no longer considers 32-bit x86 support +to be an effective use of its limited resources, and thus intends to +discontinue it. Since all recent x86 hardware from the past >10 years +is capable of the 64-bit x86 extensions, a corresponding 64-bit OS +should be used instead. + + QEMU API (QAPI) events ---------------------- -- 2.31.1

Hardly anybody still uses 32-bit x86 environments for running QEMU, so let's stop wasting our scarce CI minutes with these jobs. Signed-off-by: Thomas Huth <thuth(a)redhat.com&gt; ---  .gitlab-ci.d/crossbuilds.yml | 16 ----------------  1 file changed, 16 deletions(-)

diff --git a/.gitlab-ci.d/crossbuilds.yml b/.gitlab- ci.d/crossbuilds.yml index 101416080c..3ce51adf77 100644 --- a/.gitlab-ci.d/crossbuilds.yml +++ b/.gitlab-ci.d/crossbuilds.yml @@ -43,22 +43,6 @@ cross-arm64-user:    variables:      IMAGE: debian-arm64-cross   -cross-i386-system: -  extends: .cross_system_build_job -  needs: -    job: i386-fedora-cross-container -  variables: -    IMAGE: fedora-i386-cross -    MAKE_CHECK_ARGS: check-qtest - -cross-i386-user: -  extends: .cross_user_build_job -  needs: -    job: i386-fedora-cross-container -  variables: -    IMAGE: fedora-i386-cross -    MAKE_CHECK_ARGS: check -  cross-i386-tci:    extends: .cross_accel_build_job    timeout: 60m

On 2/3/23 17:31, Thomas Huth wrote: > qemu-system-aarch64 is a proper superset of qemu-system-arm, > and the latter was mainly still required for 32-bit KVM support. > But this 32-bit KVM arm support has been dropped in the Linux > kernel a couple of years ago already, so we don't really need > qemu-system-arm anymore, thus deprecated it now. > > Signed-off-by: Thomas Huth <thuth(a)redhat.com&gt; > --- >   docs/about/deprecated.rst | 10 ++++++++++ >   1 file changed, 10 insertions(+) > > diff --git a/docs/about/deprecated.rst b/docs/about/deprecated.rst > index a30aa8dfdf..21ce70b5c9 100644 > --- a/docs/about/deprecated.rst > +++ b/docs/about/deprecated.rst > @@ -45,6 +45,16 @@ run 32-bit guests by selecting a 32-bit CPU model, > including KVM support >   on x86_64 hosts. Thus users are recommended to reconfigure their systems >   to use the ``qemu-system-x86_64`` binary instead. > +``qemu-system-arm`` binary (since 8.0) > +'''''''''''''''''''''''''''''''''''''' > + > +``qemu-system-aarch64`` is a proper superset of ``qemu-system-arm``. The > +latter was mainly a requirement for running KVM on 32-bit arm hosts, but > +this 32-bit KVM support has been removed some years ago already (see: s/some/few/?

> +https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=541ad0150ca4 > > +). Thus the QEMU project will drop the ``qemu-system-arm`` binary in a > +future release. Use ``qemu-system-aarch64`` instead. If we unify, wouldn't it be simpler to name the single qemu-system binary emulating various ARM architectures as 'qemu-system-arm'?

qemu-system-aarch64 is a proper superset of qemu-system-arm, and the latter was mainly still required for 32-bit KVM support. But this 32-bit KVM arm support has been dropped in the Linux kernel a couple of years ago already, so we don't really need qemu-system-arm anymore, thus deprecated it now. Signed-off-by: Thomas Huth <thuth(a)redhat.com&gt; --- docs/about/deprecated.rst | 10 ++++++++++ 1 file changed, 10 insertions(+) diff --git a/docs/about/deprecated.rst b/docs/about/deprecated.rst index a30aa8dfdf..21ce70b5c9 100644 --- a/docs/about/deprecated.rst +++ b/docs/about/deprecated.rst @@ -45,6 +45,16 @@ run 32-bit guests by selecting a 32-bit CPU model, including KVM support on x86_64 hosts. Thus users are recommended to reconfigure their systems to use the ``qemu-system-x86_64`` binary instead. +``qemu-system-arm`` binary (since 8.0) +'''''''''''''''''''''''''''''''''''''' + +``qemu-system-aarch64`` is a proper superset of ``qemu-system-arm``.

On 03/03/2023 12.16, Peter Maydell wrote: > On Thu, 2 Mar 2023 at 16:31, Thomas Huth <thuth(a)redhat.com&gt; wrote: > > > > qemu-system-aarch64 is a proper superset of qemu-system-arm, > > and the latter was mainly still required for 32-bit KVM support. > > But this 32-bit KVM arm support has been dropped in the Linux > > kernel a couple of years ago already, so we don't really need > > qemu-system-arm anymore, thus deprecated it now. > > > > Signed-off-by: Thomas Huth <thuth(a)redhat.com&gt; > > --- > > docs/about/deprecated.rst | 10 ++++++++++ > > 1 file changed, 10 insertions(+) > > > > diff --git a/docs/about/deprecated.rst b/docs/about/deprecated.rst > > index a30aa8dfdf..21ce70b5c9 100644 > > --- a/docs/about/deprecated.rst > > +++ b/docs/about/deprecated.rst > > @@ -45,6 +45,16 @@ run 32-bit guests by selecting a 32-bit CPU model, including KVM support > > on x86_64 hosts. Thus users are recommended to reconfigure their systems > > to use the ``qemu-system-x86_64`` binary instead. > > > > +``qemu-system-arm`` binary (since 8.0) > > +'''''''''''''''''''''''''''''''''''''' > > + > > +``qemu-system-aarch64`` is a proper superset of ``qemu-system-arm``. > > I think this is not quite true -- at the moment if you want > "every feature we implement, 32-bit" the only way to get > that is 'qemu-system-arm -cpu max'. The '-cpu max' on > qemu-system-aarch64 is 64-bit, and we don't implement for TCG > the "-cpu max,aarch64=off" syntax that we do for KVM that would > let the user say "no 64-bit support". Ok ... so what does that mean now? ... can we continue with this patch, e.g. after rephrasing the text a little bit, or do we need to implement "-cpu max,aarch64=off" for TCG first?

For running QEMU in system emulation mode, the user needs a rather strong host system, i.e. not only an embedded low-frequency controller. All recent beefy arm host machines should support 64-bit now, it's unlikely that anybody is still seriously using QEMU on a 32-bit arm CPU, so we deprecate the 32-bit arm hosts here to finally save use some time and precious CI minutes. Signed-off-by: Thomas Huth <thuth(a)redhat.com&gt; --- docs/about/deprecated.rst | 9 +++++++++ 1 file changed, 9 insertions(+)

diff --git a/docs/about/deprecated.rst b/docs/about/deprecated.rst index 21ce70b5c9..c7113a7510 100644 --- a/docs/about/deprecated.rst +++ b/docs/about/deprecated.rst @@ -229,6 +229,15 @@ discontinue it. Since all recent x86 hardware from the past >10 years is capable of the 64-bit x86 extensions, a corresponding 64-bit OS should be used instead. +System emulation on 32-bit arm hosts (since 8.0) +'''''''''''''''''''''''''''''''''''''''''''''''' + +Since QEMU needs a strong host machine for running full system emulation, and +all recent powerful arm hosts support 64-bit, the QEMU project deprecates the +support for running any system emulation on 32-bit arm hosts in general. Use +64-bit arm hosts for system emulation instead. (Note: "user" mode emulation +continuous to be supported on 32-bit arm hosts, too)

+ QEMU API (QAPI) events ---------------------- -- 2.31.1