History log of /openbmc/qemu/docs/devel/atomics.rst (Results 1 – 20 of 20)
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Revision tags: v9.2.0, v9.1.2, v9.1.1
# b38d263b 11-Oct-2024 Peter Maydell <peter.maydell@linaro.org>

Merge tag 'for-upstream' of https://gitlab.com/bonzini/qemu into staging

* first commit for Rust support
* add CI job using Fedora + Rust nightly
* fix detection of ATOMIC128 on x86_64
* fix compila

Merge tag 'for-upstream' of https://gitlab.com/bonzini/qemu into staging

* first commit for Rust support
* add CI job using Fedora + Rust nightly
* fix detection of ATOMIC128 on x86_64
* fix compilation with Sphinx 8.1.0

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# gpg: using RSA key F13338574B662389866C7682BFFBD25F78C7AE83
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# gpg: Good signature from "Paolo Bonzini <bonzini@gnu.org>" [full]
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* tag 'for-upstream' of https://gitlab.com/bonzini/qemu:
docs: use consistent markup for footnotes
docs: avoid footnotes consisting of just URLs
docs: fix invalid footnote syntax
gitlab-ci: add Rust-enabled CI job
dockerfiles: add a Dockerfile using a nightly Rust toolchain
meson: ensure -mcx16 is passed when detecting ATOMIC128
meson: define qemu_isa_flags
meson: fix machine option for x86_version
rust: add PL011 device model
rust: add utility procedural macro crate
scripts/archive-source: find directory name for subprojects
rust: add crate to expose bindings and interfaces
meson.build: add HAVE_GLIB_WITH_ALIGNED_ALLOC flag
.gitattributes: add Rust diff and merge attributes
rust: add bindgen step as a meson dependency
configure, meson: detect Rust toolchain
build-sys: Add rust feature option
Require meson version 1.5.0

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

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# 381d2c36 11-Oct-2024 Paolo Bonzini <pbonzini@redhat.com>

docs: use consistent markup for footnotes

Unfortunately, the definition of the footnote syntax requires
the author to use the awkward escaped space "\ " in the really common
case of "footnote marker

docs: use consistent markup for footnotes

Unfortunately, the definition of the footnote syntax requires
the author to use the awkward escaped space "\ " in the really common
case of "footnote marker at end of word or sentence"; and in fact the rST
documentation's examples of footnote syntax contain only artificial
examples that do *not* use the syntax. This resulted in ugly rendering
of footnotes throughout QEMU's documentation. Ensure the space is escaped
whenever the footnote must attach to the preceding word, and also use
a named reference for clarity.

Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

show more ...


# effb0f77 11-Oct-2024 Paolo Bonzini <pbonzini@redhat.com>

docs: fix invalid footnote syntax

All footnotes must come after a separator in reStructuredText. Fix the
two files in which this does not happen.

This mistake causes the link to be rendered litera

docs: fix invalid footnote syntax

All footnotes must come after a separator in reStructuredText. Fix the
two files in which this does not happen.

This mistake causes the link to be rendered literally:

...from the venv itself[#distlib]_. If no...

and is caught by Sphinx 8.1.0 as an unreferenced footnote.

Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

show more ...


Revision tags: v9.1.0
# 2fd8df93 02-Apr-2024 Peter Maydell <peter.maydell@linaro.org>

Merge tag 'pull-trivial-patches' of https://gitlab.com/mjt0k/qemu into staging

trivial patches for 2024-04-02

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Merge tag 'pull-trivial-patches' of https://gitlab.com/mjt0k/qemu into staging

trivial patches for 2024-04-02

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* tag 'pull-trivial-patches' of https://gitlab.com/mjt0k/qemu:
hmp: Add help information for watchdog action: inject-nmi
Fix some typos in documentation (found by codespell)
fpu/softfloat: Remove mention of TILE-Gx target
usb-audio: Fix invalid values in AudioControl descriptors

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

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# f6822fee 31-Mar-2024 Stefan Weil <sw@weilnetz.de>

Fix some typos in documentation (found by codespell)

Signed-off-by: Stefan Weil <sw@weilnetz.de>
Reviewed-by: Michael Tokarev <mjt@tls.msk.ru>
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>


# 80bdd58a 06-Jun-2023 Richard Henderson <richard.henderson@linaro.org>

Merge tag 'for-upstream' of https://gitlab.com/bonzini/qemu into staging

* finish atomics revamp
* meson.build tweaks
* revert avocado update
* always upgrade/downgrade locally installed Python pack

Merge tag 'for-upstream' of https://gitlab.com/bonzini/qemu into staging

* finish atomics revamp
* meson.build tweaks
* revert avocado update
* always upgrade/downgrade locally installed Python packages
* switch from submodules to subprojects
* remove --with-git= option
* rename --enable-pypi to --enable-download, control submodules and subprojects too

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* tag 'for-upstream' of https://gitlab.com/bonzini/qemu: (21 commits)
configure: remove --with-git-submodules=
build: remove git submodule handling from main makefile
meson: subprojects: replace berkeley-{soft,test}float-3 with wraps
pc-bios/s390-ccw: always build network bootloader
configure: move SLOF submodule handling to pc-bios/s390-ccw
meson: subprojects: replace submodules with wrap files
build: log submodule update from git-submodule.sh
git-submodule: allow partial update of .git-submodule-status
configure: rename --enable-pypi to --enable-download, control subprojects too
configure: remove --with-git= option
mkvenv: always pass locally-installed packages to pip
tests: Use separate virtual environment for avocado
Revert "tests/requirements.txt: bump up avocado-framework version to 101.0"
scsi/qemu-pr-helper: Drop support for 'old' libmultipath API
meson.build: Use -Wno-undef only for SDL2 versions that need it
meson.build: Group the audio backend entries in a separate summary section
meson.build: Group the network backend entries in a separate summary section
meson.build: Group the UI entries in a separate summary section
scripts: remove dead file
atomics: eliminate mb_read/mb_set
...

Signed-off-by: Richard Henderson <richard.henderson@linaro.org>

show more ...


Revision tags: v8.0.0
# 06831001 03-Mar-2023 Paolo Bonzini <pbonzini@redhat.com>

atomics: eliminate mb_read/mb_set

qatomic_mb_read and qatomic_mb_set were the very first atomic primitives
introduced for QEMU; their semantics are unclear and they provide a false
sense of safety.

atomics: eliminate mb_read/mb_set

qatomic_mb_read and qatomic_mb_set were the very first atomic primitives
introduced for QEMU; their semantics are unclear and they provide a false
sense of safety.

The last use of qatomic_mb_read() has been removed, so delete it.
qatomic_mb_set() instead can survive as an optimized
qatomic_set()+smp_mb(), similar to Linux's smp_store_mb(), but
rename it to qatomic_set_mb() to match the order of the two
operations.

Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

show more ...


# 1cc6e1a2 22-Apr-2023 Richard Henderson <richard.henderson@linaro.org>

Merge tag 'for-upstream' of https://gitlab.com/bonzini/qemu into staging

* Optional use of Meson wrap for slirp
* Coverity fixes
* Avoid -Werror=maybe-uninitialized
* Mark coroutine QMP command func

Merge tag 'for-upstream' of https://gitlab.com/bonzini/qemu into staging

* Optional use of Meson wrap for slirp
* Coverity fixes
* Avoid -Werror=maybe-uninitialized
* Mark coroutine QMP command functions as coroutine_fn
* Mark functions that suspend as coroutine_mixed_fn
* target/i386: Fix SGX CPUID leaf
* First batch of qatomic_mb_read() removal
* Small atomic.rst improvement
* NBD cleanup
* Update libvirt-ci submodule

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* tag 'for-upstream' of https://gitlab.com/bonzini/qemu: (25 commits)
tests: lcitool: Switch to OpenSUSE Leap 15.4
tests: libvirt-ci: Update to commit '2fa24dce8bc'
configure: Honour cross-prefix when finding ObjC compiler
coverity: unify Fedora dockerfiles
nbd: a BlockExport always has a BlockBackend
docs: explain effect of smp_read_barrier_depends() on modern architectures
qemu-coroutine: remove qatomic_mb_read()
postcopy-ram: do not use qatomic_mb_read
block-backend: remove qatomic_mb_read()
target/i386: Change wrong XFRM value in SGX CPUID leaf
monitor: mark mixed functions that can suspend
migration: mark mixed functions that can suspend
io: mark mixed functions that can suspend
qapi-gen: mark coroutine QMP command functions as coroutine_fn
target/mips: tcg: detect out-of-bounds accesses to cpu_gpr and cpu_gpr_hi
coverity: update COMPONENTS.md
lasi: fix RTC migration
target/i386: Avoid unreachable variable declaration in mmu_translate()
configure: Avoid -Werror=maybe-uninitialized
tests: bios-tables-test: replace memset with initializer
...

Signed-off-by: Richard Henderson <richard.henderson@linaro.org>

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# 000eebcf 07-Apr-2023 Paolo Bonzini <pbonzini@redhat.com>

docs: explain effect of smp_read_barrier_depends() on modern architectures

The documentation for smp_read_barrier_depends() does not mention the architectures
for which it is an optimization, for ex

docs: explain effect of smp_read_barrier_depends() on modern architectures

The documentation for smp_read_barrier_depends() does not mention the architectures
for which it is an optimization, for example ARM and PPC. As a result, it is not
clear to the reader why one would use it. Relegate Alpha to a footnote together
with other architectures where it is equivalent to smp_rmb().

Suggested-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

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# be4033d7 15-Mar-2023 Peter Maydell <peter.maydell@linaro.org>

Merge tag 'for-upstream' of https://gitlab.com/bonzini/qemu into staging

small bug fixes

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Merge tag 'for-upstream' of https://gitlab.com/bonzini/qemu into staging

small bug fixes

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# gpg: Good signature from "Paolo Bonzini <bonzini@gnu.org>" [full]
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# Primary key fingerprint: 46F5 9FBD 57D6 12E7 BFD4 E2F7 7E15 100C CD36 69B1
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* tag 'for-upstream' of https://gitlab.com/bonzini/qemu:
vl: defuse PID file path resolve error
hw/intc/ioapic: Update KVM routes before redelivering IRQ, on RTE update
docs/devel: clarify further the semantics of RMW operations
Fix build without CONFIG_XEN_EMU

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

show more ...


# 3b31669e 09-Mar-2023 Paolo Bonzini <pbonzini@redhat.com>

docs/devel: clarify further the semantics of RMW operations

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>


# 7b0f0aa5 07-Mar-2023 Peter Maydell <peter.maydell@linaro.org>

Merge tag 'for-upstream-mb' of https://gitlab.com/bonzini/qemu into staging

* Fix missing memory barriers
* Fix comments about memory ordering

# -----BEGIN PGP SIGNATURE-----
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Merge tag 'for-upstream-mb' of https://gitlab.com/bonzini/qemu into staging

* Fix missing memory barriers
* Fix comments about memory ordering

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# gpg: using RSA key F13338574B662389866C7682BFFBD25F78C7AE83
# gpg: issuer "pbonzini@redhat.com"
# gpg: Good signature from "Paolo Bonzini <bonzini@gnu.org>" [full]
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# Primary key fingerprint: 46F5 9FBD 57D6 12E7 BFD4 E2F7 7E15 100C CD36 69B1
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* tag 'for-upstream-mb' of https://gitlab.com/bonzini/qemu:
async: clarify usage of barriers in the polling case
async: update documentation of the memory barriers
physmem: add missing memory barrier
qemu-coroutine-lock: add smp_mb__after_rmw()
aio-wait: switch to smp_mb__after_rmw()
edu: add smp_mb__after_rmw()
qemu-thread-win32: cleanup, fix, document QemuEvent
qemu-thread-posix: cleanup, fix, document QemuEvent
qatomic: add smp_mb__before/after_rmw()

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

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# ff00bed1 02-Mar-2023 Paolo Bonzini <pbonzini@redhat.com>

qatomic: add smp_mb__before/after_rmw()

On ARM, seqcst loads and stores (which QEMU does not use) are compiled
respectively as LDAR and STLR instructions. Even though LDAR is
also used for load-acq

qatomic: add smp_mb__before/after_rmw()

On ARM, seqcst loads and stores (which QEMU does not use) are compiled
respectively as LDAR and STLR instructions. Even though LDAR is
also used for load-acquire operations, it also waits for all STLRs to
leave the store buffer. Thus, LDAR and STLR alone are load-acquire
and store-release operations, but LDAR also provides store-against-load
ordering as long as the previous store is a STLR.

Compare this to ARMv7, where store-release is DMB+STR and load-acquire
is LDR+DMB, but an additional DMB is needed between store-seqcst and
load-seqcst (e.g. DMB+STR+DMB+LDR+DMB); or with x86, where MOV provides
load-acquire and store-release semantics and the two can be reordered.

Likewise, on ARM sequentially consistent read-modify-write operations only
need to use LDAXR and STLXR respectively for the load and the store, while
on x86 they need to use the stronger LOCK prefix.

In a strange twist of events, however, the _stronger_ semantics
of the ARM instructions can end up causing bugs on ARM, not on x86.
The problems occur when seqcst atomics are mixed with relaxed atomics.

QEMU's atomics try to bridge the Linux API (that most of the developers
are familiar with) and the C11 API, and the two have a substantial
difference:

- in Linux, strongly-ordered atomics such as atomic_add_return() affect
the global ordering of _all_ memory operations, including for example
READ_ONCE()/WRITE_ONCE()

- in C11, sequentially consistent atomics (except for seq-cst fences)
only affect the ordering of sequentially consistent operations.
In particular, since relaxed loads are done with LDR on ARM, they are
not ordered against seqcst stores (which are done with STLR).

QEMU implements high-level synchronization primitives with the idea that
the primitives contain the necessary memory barriers, and the callers can
use relaxed atomics (qatomic_read/qatomic_set) or even regular accesses.
This is very much incompatible with the C11 view that seqcst accesses
are only ordered against other seqcst accesses, and requires using seqcst
fences as in the following example:

qatomic_set(&y, 1); qatomic_set(&x, 1);
smp_mb(); smp_mb();
... qatomic_read(&x) ... ... qatomic_read(&y) ...

When a qatomic_*() read-modify write operation is used instead of one
or both stores, developers that are more familiar with the Linux API may
be tempted to omit the smp_mb(), which will work on x86 but not on ARM.

This nasty difference between Linux and C11 read-modify-write operations
has already caused issues in util/async.c and more are being found.
Provide something similar to Linux smp_mb__before/after_atomic(); this
has the double function of documenting clearly why there is a memory
barrier, and avoiding a double barrier on x86 and s390x systems.

The new macro can already be put to use in qatomic_mb_set().

Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

show more ...


# aaa90fed 06-Jan-2023 Peter Maydell <peter.maydell@linaro.org>

Merge tag 'pull-tcg-20230105' of https://gitlab.com/rth7680/qemu into staging

Fix race conditions in new user-only vma tracking.
Add tcg backend paired register allocation.
Cleanup tcg backend funct

Merge tag 'pull-tcg-20230105' of https://gitlab.com/rth7680/qemu into staging

Fix race conditions in new user-only vma tracking.
Add tcg backend paired register allocation.
Cleanup tcg backend function call abi.

# gpg: Signature made Fri 06 Jan 2023 03:12:17 GMT
# gpg: using RSA key 7A481E78868B4DB6A85A05C064DF38E8AF7E215F
# gpg: issuer "richard.henderson@linaro.org"
# gpg: Good signature from "Richard Henderson <richard.henderson@linaro.org>" [full]
# Primary key fingerprint: 7A48 1E78 868B 4DB6 A85A 05C0 64DF 38E8 AF7E 215F

* tag 'pull-tcg-20230105' of https://gitlab.com/rth7680/qemu: (47 commits)
tests/tcg/multiarch: add vma-pthread.c
accel/tcg: Handle false negative lookup in page_check_range
accel/tcg: Use g_free_rcu for user-exec interval trees
accel/tcg: Fix tb_invalidate_phys_page_unwind
tcg: Add TCGHelperInfo argument to tcg_out_call
tcg/aarch64: Merge tcg_out_callr into tcg_out_call
tcg: Move ffi_cif pointer into TCGHelperInfo
tcg: Factor init_ffi_layouts() out of tcg_context_init()
tcg: Convert typecode_to_ffi from array to function
tcg: Reorg function calls
tcg: Use output_pref wrapper function
tcg: Vary the allocation size for TCGOp
tcg: Pass number of arguments to tcg_emit_op() / tcg_op_insert_*()
accel/tcg/plugin: Use copy_op in append_{udata,mem}_cb
accel/tcg/plugin: Avoid duplicate copy in copy_call
accel/tcg/plugin: Don't search for the function pointer index
tcg: Use TCG_CALL_ARG_EVEN for TCI special case
tcg: Replace TCG_TARGET_EXTEND_ARGS with TCG_TARGET_CALL_ARG_I32
tcg: Replace TCG_TARGET_CALL_ALIGN_ARGS with TCG_TARGET_CALL_ARG_I64
tcg: Introduce TCGCallReturnKind and TCGCallArgumentKind
...

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

show more ...


Revision tags: v7.2.0
# 5e97a28a 30-Nov-2022 Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>

tcg: convert tcg/README to rst

Convert tcg/README to rst and move it to docs/devel as a new "TCG Intermediate
Representation" page. There are a few minor changes to improve the aesthetic
of the fina

tcg: convert tcg/README to rst

Convert tcg/README to rst and move it to docs/devel as a new "TCG Intermediate
Representation" page. There are a few minor changes to improve the aesthetic
of the final output which are as follows:

- Rename the title from "Tiny Code Generator - Fabrice Bellard" to "TCG
Intermediate Representation"

- Remove the section numbering

- Add the missing parameters to the ssadd_vec operations in the "Host
vector operations" section

- Change the path to the Atomic Operations document to use a proper
reference

- Replace tcg/README in tcg.rst with a proper reference to the new document

Signed-off-by: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>
Reviewed-by: Fabiano Rosas <farosas@suse.de>
Message-Id: <20221130100434.64207-2-mark.cave-ayland@ilande.co.uk>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>

show more ...


Revision tags: v7.0.0, v6.2.0, v6.1.0, v5.2.0
# 8c1c0792 24-Sep-2020 Peter Maydell <peter.maydell@linaro.org>

Merge remote-tracking branch 'remotes/stefanha/tags/block-pull-request' into staging

Pull request

This includes the atomic_ -> qatomic_ rename that touches many files and is
prone to conflicts.

#

Merge remote-tracking branch 'remotes/stefanha/tags/block-pull-request' into staging

Pull request

This includes the atomic_ -> qatomic_ rename that touches many files and is
prone to conflicts.

# gpg: Signature made Wed 23 Sep 2020 17:08:43 BST
# gpg: using RSA key 8695A8BFD3F97CDAAC35775A9CA4ABB381AB73C8
# gpg: Good signature from "Stefan Hajnoczi <stefanha@redhat.com>" [full]
# gpg: aka "Stefan Hajnoczi <stefanha@gmail.com>" [full]
# Primary key fingerprint: 8695 A8BF D3F9 7CDA AC35 775A 9CA4 ABB3 81AB 73C8

* remotes/stefanha/tags/block-pull-request:
qemu/atomic.h: rename atomic_ to qatomic_
tests: add test-fdmon-epoll
fdmon-poll: reset npfd when upgrading to fdmon-epoll
gitmodules: add qemu.org vbootrom submodule
gitmodules: switch to qemu.org meson mirror
gitmodules: switch to qemu.org qboot mirror
docs/system: clarify deprecation schedule
virtio-crypto: don't modify elem->in/out_sg
virtio-blk: undo destructive iov_discard_*() operations
util/iov: add iov_discard_undo()
virtio: add vhost-user-fs-ccw device
libvhost-user: handle endianness as mandated by the spec
MAINTAINERS: add Stefan Hajnoczi as block/nvme.c maintainer

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

show more ...


# d73415a3 23-Sep-2020 Stefan Hajnoczi <stefanha@redhat.com>

qemu/atomic.h: rename atomic_ to qatomic_

clang's C11 atomic_fetch_*() functions only take a C11 atomic type
pointer argument. QEMU uses direct types (int, etc) and this causes a
compiler error when

qemu/atomic.h: rename atomic_ to qatomic_

clang's C11 atomic_fetch_*() functions only take a C11 atomic type
pointer argument. QEMU uses direct types (int, etc) and this causes a
compiler error when a QEMU code calls these functions in a source file
that also included <stdatomic.h> via a system header file:

$ CC=clang CXX=clang++ ./configure ... && make
../util/async.c:79:17: error: address argument to atomic operation must be a pointer to _Atomic type ('unsigned int *' invalid)

Avoid using atomic_*() names in QEMU's atomic.h since that namespace is
used by <stdatomic.h>. Prefix QEMU's APIs with 'q' so that atomic.h
and <stdatomic.h> can co-exist. I checked /usr/include on my machine and
searched GitHub for existing "qatomic_" users but there seem to be none.

This patch was generated using:

$ git grep -h -o '\<atomic\(64\)\?_[a-z0-9_]\+' include/qemu/atomic.h | \
sort -u >/tmp/changed_identifiers
$ for identifier in $(</tmp/changed_identifiers); do
sed -i "s%\<$identifier\>%q$identifier%g" \
$(git grep -I -l "\<$identifier\>")
done

I manually fixed line-wrap issues and misaligned rST tables.

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Acked-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <20200923105646.47864-1-stefanha@redhat.com>

show more ...


Revision tags: v5.0.0
# e33d61cc 13-Apr-2020 Peter Maydell <peter.maydell@linaro.org>

Merge remote-tracking branch 'remotes/bonzini/tags/for-upstream' into staging

Bugfixes, and reworking of the atomics documentation.

# gpg: Signature made Mon 13 Apr 2020 07:56:22 BST
# gpg:

Merge remote-tracking branch 'remotes/bonzini/tags/for-upstream' into staging

Bugfixes, and reworking of the atomics documentation.

# gpg: Signature made Mon 13 Apr 2020 07:56:22 BST
# gpg: using RSA key F13338574B662389866C7682BFFBD25F78C7AE83
# gpg: issuer "pbonzini@redhat.com"
# gpg: Good signature from "Paolo Bonzini <bonzini@gnu.org>" [full]
# gpg: aka "Paolo Bonzini <pbonzini@redhat.com>" [full]
# Primary key fingerprint: 46F5 9FBD 57D6 12E7 BFD4 E2F7 7E15 100C CD36 69B1
# Subkey fingerprint: F133 3857 4B66 2389 866C 7682 BFFB D25F 78C7 AE83

* remotes/bonzini/tags/for-upstream:
module: increase dirs array size by one
memory: Do not allow direct write access to rom_device regions
vl.c: error out if -mem-path is used together with -M memory-backend
rcu: do not mention atomic_mb_read/set in documentation
atomics: update documentation
atomics: convert to reStructuredText
oslib-posix: take lock before qemu_cond_broadcast
piix: fix xenfv regression, add compat machine xenfv-4.2

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

show more ...


# de99dab0 06-Apr-2020 Paolo Bonzini <pbonzini@redhat.com>

atomics: update documentation

Some of the constraints on operand sizes have been relaxed, so adjust the
documentation.

Deprecate atomic_mb_read and atomic_mb_set; it is not really possible to
use t

atomics: update documentation

Some of the constraints on operand sizes have been relaxed, so adjust the
documentation.

Deprecate atomic_mb_read and atomic_mb_set; it is not really possible to
use them correctly because they do not interoperate with sequentially-consistent
RMW operations.

Finally, extend the memory barrier pairing section to cover acquire and
release semantics in general, roughly based on the KVM Forum 2016 talk,
"<atomic.h> weapons".

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

show more ...


# 15e8699f 06-Apr-2020 Paolo Bonzini <pbonzini@redhat.com>

atomics: convert to reStructuredText

No attempts to fix or update the text; these are left for the next
patch in the series.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>