| Message ID | 20250412164315.36161-1-richard.henderson@linaro.org |
|---|---|
| State | New |
| Headers | show |
| Series | [for-10.0] docs: Document removal of 64-bit on 32-bit emulation | expand |
On Sat, Apr 12, 2025 at 09:43:15AM -0700, Richard Henderson wrote: > With acce728cbc6c we disallowed configuring 64-bit guests on > 32-bit hosts, but forgot to document that in removed-features. > > Signed-off-by: Richard Henderson <richard.henderson@linaro.org> > --- > docs/about/removed-features.rst | 9 +++++++++ > 1 file changed, 9 insertions(+) > > diff --git a/docs/about/removed-features.rst b/docs/about/removed-features.rst > index 2527a91795..790a5e481c 100644 > --- a/docs/about/removed-features.rst > +++ b/docs/about/removed-features.rst > @@ -858,6 +858,15 @@ QEMU. 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. > > +32-bit hosts for 64-bit guests (removed in 10.0) > +'''''''''''''''''''''''''''''''''''''''''''''''' > + > +In general, 32-bit hosts cannot support the memory space or atomicity > +requirements of 64-bit guests. Prior to 10.0, QEMU attempted to > +work around the atomicity issues in system mode by running all vCPUs > +in a single thread context; in user mode atomicity was simply broken. > +From 10.0, QEMU has disabled configuration of 64-bit guests on 32-bit hosts. > + > Guest Emulator ISAs > ------------------- Reviewed-by: Daniel P. Berrangé <berrange@redhat.com> With regards, Daniel
Richard Henderson <richard.henderson@linaro.org> writes: > With acce728cbc6c we disallowed configuring 64-bit guests on > 32-bit hosts, but forgot to document that in removed-features. > > Signed-off-by: Richard Henderson <richard.henderson@linaro.org> Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
On 12/4/25 18:43, Richard Henderson wrote: > With acce728cbc6c we disallowed configuring 64-bit guests on > 32-bit hosts, but forgot to document that in removed-features. > > Signed-off-by: Richard Henderson <richard.henderson@linaro.org> > --- > docs/about/removed-features.rst | 9 +++++++++ > 1 file changed, 9 insertions(+) Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
On Sat, Apr 12, 2025 at 12:43 PM Richard Henderson <richard.henderson@linaro.org> wrote: > > With acce728cbc6c we disallowed configuring 64-bit guests on > 32-bit hosts, but forgot to document that in removed-features. > > Signed-off-by: Richard Henderson <richard.henderson@linaro.org> > --- > docs/about/removed-features.rst | 9 +++++++++ > 1 file changed, 9 insertions(+) Merged for 10.0 via Michael Tokarev's trivial patches pull request. Stefan > > diff --git a/docs/about/removed-features.rst b/docs/about/removed-features.rst > index 2527a91795..790a5e481c 100644 > --- a/docs/about/removed-features.rst > +++ b/docs/about/removed-features.rst > @@ -858,6 +858,15 @@ QEMU. 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. > > +32-bit hosts for 64-bit guests (removed in 10.0) > +'''''''''''''''''''''''''''''''''''''''''''''''' > + > +In general, 32-bit hosts cannot support the memory space or atomicity > +requirements of 64-bit guests. Prior to 10.0, QEMU attempted to > +work around the atomicity issues in system mode by running all vCPUs > +in a single thread context; in user mode atomicity was simply broken. > +From 10.0, QEMU has disabled configuration of 64-bit guests on 32-bit hosts. > + > Guest Emulator ISAs > ------------------- > > -- > 2.43.0 >
On 4/14/25 08:16, Stefan Hajnoczi wrote: > On Sat, Apr 12, 2025 at 12:43 PM Richard Henderson > <richard.henderson@linaro.org> wrote: >> >> With acce728cbc6c we disallowed configuring 64-bit guests on >> 32-bit hosts, but forgot to document that in removed-features. >> >> Signed-off-by: Richard Henderson <richard.henderson@linaro.org> >> --- >> docs/about/removed-features.rst | 9 +++++++++ >> 1 file changed, 9 insertions(+) > > Merged for 10.0 via Michael Tokarev's trivial patches pull request. Thanks, guys. r~
diff --git a/docs/about/removed-features.rst b/docs/about/removed-features.rst index 2527a91795..790a5e481c 100644 --- a/docs/about/removed-features.rst +++ b/docs/about/removed-features.rst @@ -858,6 +858,15 @@ QEMU. 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. +32-bit hosts for 64-bit guests (removed in 10.0) +'''''''''''''''''''''''''''''''''''''''''''''''' + +In general, 32-bit hosts cannot support the memory space or atomicity +requirements of 64-bit guests. Prior to 10.0, QEMU attempted to +work around the atomicity issues in system mode by running all vCPUs +in a single thread context; in user mode atomicity was simply broken. +From 10.0, QEMU has disabled configuration of 64-bit guests on 32-bit hosts. + Guest Emulator ISAs -------------------
With acce728cbc6c we disallowed configuring 64-bit guests on 32-bit hosts, but forgot to document that in removed-features. Signed-off-by: Richard Henderson <richard.henderson@linaro.org> --- docs/about/removed-features.rst | 9 +++++++++ 1 file changed, 9 insertions(+)