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Peter Anvin" , Ajay Kaher , Alexey Makhalov , Broadcom internal kernel review list , Paolo Bonzini , Vitaly Kuznetsov , Boris Ostrovsky , xen-devel@lists.xenproject.org, Denis Efremov , Jens Axboe Subject: [PATCH v4 0/6] x86: Cleanups around slow_down_io() Date: Mon, 19 Jan 2026 19:26:26 +0100 Message-ID: <20260119182632.596369-1-jgross@suse.com> X-Mailer: git-send-email 2.52.0 Precedence: bulk X-Mailing-List: virtualization@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Spamd-Result: default: False [-3.01 / 50.00]; BAYES_HAM(-3.00)[100.00%]; MID_CONTAINS_FROM(1.00)[]; NEURAL_HAM_LONG(-1.00)[-1.000]; R_MISSING_CHARSET(0.50)[]; R_DKIM_ALLOW(-0.20)[suse.com:s=susede1]; NEURAL_HAM_SHORT(-0.20)[-1.000]; MIME_GOOD(-0.10)[text/plain]; MX_GOOD(-0.01)[]; URIBL_BLOCKED(0.00)[suse.com:dkim,suse.com:mid,imap1.dmz-prg2.suse.org:helo,imap1.dmz-prg2.suse.org:rdns]; FROM_HAS_DN(0.00)[]; FUZZY_RATELIMITED(0.00)[rspamd.com]; ARC_NA(0.00)[]; TO_DN_SOME(0.00)[]; RCPT_COUNT_TWELVE(0.00)[20]; MIME_TRACE(0.00)[0:+]; TO_MATCH_ENVRCPT_ALL(0.00)[]; RCVD_VIA_SMTP_AUTH(0.00)[]; FROM_EQ_ENVFROM(0.00)[]; DKIM_SIGNED(0.00)[suse.com:s=susede1]; DBL_BLOCKED_OPENRESOLVER(0.00)[suse.com:dkim,suse.com:mid]; RBL_SPAMHAUS_BLOCKED_OPENRESOLVER(0.00)[2a07:de40:b281:104:10:150:64:97:from]; RCVD_COUNT_TWO(0.00)[2]; RCVD_TLS_ALL(0.00)[]; SPAMHAUS_XBL(0.00)[2a07:de40:b281:104:10:150:64:97:from]; DKIM_TRACE(0.00)[suse.com:+] X-Spam-Flag: NO X-Spam-Score: -3.01 X-Rspamd-Queue-Id: CDD235BCCE X-Rspamd-Action: no action X-Rspamd-Server: rspamd2.dmz-prg2.suse.org X-Spam-Level: While looking at paravirt cleanups I stumbled over slow_down_io() and the related REALLY_SLOW_IO define. Do several cleanups, resulting in a deletion of REALLY_SLOW_IO and the io_delay() paravirt function hook. Patch 4 is removing the config options for selecting the default delay mechanism and sets the default to "no delay". This is in preparation of removing the io_delay() functionality completely, as suggested by Ingo Molnar. Patch 5 is adding an additional config option allowing to avoid building io_delay.c (default is still to build it). Changes in V2: - patches 2 and 3 of V1 have been applied - new patches 4 and 5 Changes in V3: - rebase to tip/master kernel branch Changes in V4: - add patch 1 as prereq patch to the series Juergen Gross (6): x86/irqflags: Fix build failure x86/paravirt: Replace io_delay() hook with a bool block/floppy: Don't use REALLY_SLOW_IO for delays x86/io: Remove REALLY_SLOW_IO handling x86/io_delay: Switch io_delay() default mechanism to "none" x86/io_delay: Add config option for controlling build of io_delay. arch/x86/Kconfig | 8 +++ arch/x86/Kconfig.debug | 30 ---------- arch/x86/include/asm/floppy.h | 31 ++++++++-- arch/x86/include/asm/io.h | 19 ++++--- arch/x86/include/asm/irqflags.h | 6 +- arch/x86/include/asm/paravirt-base.h | 6 ++ arch/x86/include/asm/paravirt.h | 11 ---- arch/x86/include/asm/paravirt_types.h | 2 - arch/x86/kernel/Makefile | 3 +- arch/x86/kernel/cpu/vmware.c | 2 +- arch/x86/kernel/io_delay.c | 81 +-------------------------- arch/x86/kernel/kvm.c | 8 +-- arch/x86/kernel/paravirt.c | 3 +- arch/x86/kernel/setup.c | 4 +- arch/x86/xen/enlighten_pv.c | 6 +- drivers/block/floppy.c | 2 - 16 files changed, 63 insertions(+), 159 deletions(-) -- 2.52.0