• Luis R. Rodriguez's avatar
    x86/rtc: Replace paravirt rtc check with platform legacy quirk · 8d152e7a
    Luis R. Rodriguez authored
    We have 4 types of x86 platforms that disable RTC:
    
      * Intel MID
      * Lguest - uses paravirt
      * Xen dom-U - uses paravirt
      * x86 on legacy systems annotated with an ACPI legacy flag
    
    We can consolidate all of these into a platform specific legacy
    quirk set early in boot through i386_start_kernel() and through
    x86_64_start_reservations(). This deals with the RTC quirks which
    we can rely on through the hardware subarch, the ACPI check can
    be dealt with separately.
    
    For Xen things are bit more complex given that the @X86_SUBARCH_XEN
    x86_hardware_subarch is shared on for Xen which uses the PV path for
    both domU and dom0. Since the semantics for differentiating between
    the two are Xen specific we provide a platform helper to help override
    default legacy features -- x86_platform.set_legacy_features(). Use
    of this helper is highly discouraged, its only purpose should be
    to account for the lack of semantics available within your given
    x86_hardware_subarch.
    
    As per 0-day, this bumps the vmlinux size using i386-tinyconfig as
    follows:
    
    TOTAL   TEXT   init.text    x86_early_init_platform_quirks()
    +70     +62    +62          +43
    
    Only 8 bytes overhead total, as the main increase in size is
    all removed via __init.
    Suggested-by: Ingo Molnar's avatarIngo Molnar <mingo@kernel.org>
    Signed-off-by: default avatarLuis R. Rodriguez <mcgrof@kernel.org>
    Reviewed-by: default avatarJuergen Gross <jgross@suse.com>
    Cc: Andy Lutomirski <luto@amacapital.net>
    Cc: Borislav Petkov <bp@alien8.de>
    Cc: Brian Gerst <brgerst@gmail.com>
    Cc: Denys Vlasenko <dvlasenk@redhat.com>
    Cc: H. Peter Anvin <hpa@zytor.com>
    Cc: Linus Torvalds <torvalds@linux-foundation.org>
    Cc: Peter Zijlstra <peterz@infradead.org>
    Cc: Thomas Gleixner <tglx@linutronix.de>
    Cc: andrew.cooper3@citrix.com
    Cc: andriy.shevchenko@linux.intel.com
    Cc: bigeasy@linutronix.de
    Cc: boris.ostrovsky@oracle.com
    Cc: david.vrabel@citrix.com
    Cc: ffainelli@freebox.fr
    Cc: george.dunlap@citrix.com
    Cc: glin@suse.com
    Cc: jlee@suse.com
    Cc: josh@joshtriplett.org
    Cc: julien.grall@linaro.org
    Cc: konrad.wilk@oracle.com
    Cc: kozerkov@parallels.com
    Cc: lenb@kernel.org
    Cc: lguest@lists.ozlabs.org
    Cc: linux-acpi@vger.kernel.org
    Cc: lv.zheng@intel.com
    Cc: matt@codeblueprint.co.uk
    Cc: mbizon@freebox.fr
    Cc: rjw@rjwysocki.net
    Cc: robert.moore@intel.com
    Cc: rusty@rustcorp.com.au
    Cc: tiwai@suse.de
    Cc: toshi.kani@hp.com
    Cc: xen-devel@lists.xensource.com
    Link: http://lkml.kernel.org/r/1460592286-300-5-git-send-email-mcgrof@kernel.orgSigned-off-by: Ingo Molnar's avatarIngo Molnar <mingo@kernel.org>
    8d152e7a
head32.c 1.22 KB