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So the reserve_ebda_region() code has accumulated a number of
problems over the years that make it really difficult to read
and understand:
- The calculation of 'lowmem' and 'ebda_addr' is an unnecessarily
interleaved mess of first lowmem, then ebda_addr, then lowmem tweaks...
- 'lowmem' here means 'super low mem' - i.e. 16-bit addressable memory. In other
parts of the x86 code 'lowmem' means 32-bit addressable memory... This makes it
super confusing to read.
- It does not help at all that we have various memory range markers, half of which
are 'start of range', half of which are 'end of range' - but this crucial
property is not obvious in the naming at all ... gave me a headache trying to
understand all this.
- Also, the 'ebda_addr' name sucks: it highlights that it's an address (which is
obvious, all values here are addresses!), while it does not highlight that it's
the _start_ of the EBDA region ...
- 'BIOS_LOWMEM_KILOBYTES' says a lot of things, except that this is the only value
that is a pointer to a value, not a memory range address!
- The function name itself is a misnomer: it says 'reserve_ebda_region()' while
its main purpose is to reserve all the firmware ROM typically between 640K and
1MB, while the 'EBDA' part is only a small part of that ...
- Likewise, the paravirt quirk flag name 'ebda_search' is misleading as well: this
too should be about whether to reserve firmware areas in the paravirt case.
- In fact thinking about this as 'end of RAM' is confusing: what this function
*really* wants to reserve is firmware data and code areas! Once the thinking is
inverted from a mixed 'ram' and 'reserved firmware area' notion to a pure
'reserved area' notion everything becomes a lot clearer.
To improve all this rewrite the whole code (without changing the logic):
- Firstly invert the naming from 'lowmem end' to 'BIOS reserved area start'
and propagate this concept through all the variable names and constants.
BIOS_RAM_SIZE_KB_PTR // was: BIOS_LOWMEM_KILOBYTES
BIOS_START_MIN // was: INSANE_CUTOFF
ebda_start // was: ebda_addr
bios_start // was: lowmem
BIOS_START_MAX // was: LOWMEM_CAP
- Then clean up the name of the function itself by renaming it
to reserve_bios_regions() and renaming the ::ebda_search paravirt
flag to ::reserve_bios_regions.
- Fix up all the comments (fix typos), harmonize and simplify their
formulation and remove comments that become unnecessary due to
the much better naming all around.
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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As per hpa CE4100 platforms can also disable pnpbios:
http://lkml.kernel.org/r/5702B5C2.7070101@zytor.com
Then Sebastian also recently noted that CE4100 also disables
RTC probe, to do that Sebastian had long ago added the RTC
of_have_populated_dt() check, he noted that it was meant to
skip the RTC probe on all OF platforms but as of now, CE4100
was the only x86 DT using this.
We can just fold this requirement into the platform quirk
then. This now means that all of these match platform quirks
for pnpbios and RTC preferences:
* X86_SUBARCH_XEN
* X86_SUBARCH_LGUEST
* X86_SUBARCH_INTEL_MID
* X86_SUBARCH_CE4100
Also see:
http://lkml.kernel.org/r/570B52EA.60300@linutronix.de
Suggested-by: H. Peter Anvin <hpa@zytor.com>
Suggested-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Luis R. Rodriguez <mcgrof@kernel.org>
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: 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: boris.ostrovsky@oracle.com
Cc: david.vrabel@citrix.com
Cc: ffainelli@freebox.fr
Cc: george.dunlap@citrix.com
Cc: glin@suse.com
Cc: jgross@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/1460592286-300-17-git-send-email-mcgrof@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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As per hpa Intel MID platforms can also disable pnpbios:
ttp://lkml.kernel.org/r/5702B5C2.7070101@zytor.com
As per 0-day, this bumps the vmlinux size using i386-tinyconfig as
follows:
TOTAL TEXT init.text x86_early_init_platform_quirks()
-8 -8 -8 -8
Suggested-by: H. Peter Anvin <hpa@zytor.com>
Signed-off-by: Luis R. Rodriguez <mcgrof@kernel.org>
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: 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: jgross@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/1460592286-300-16-git-send-email-mcgrof@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Since we are removing paravirt_enabled() replace it with a
logical equivalent. Even though PNPBIOS is x86 specific we
add an arch-specific type call, which can be implemented by
any architecture to show how other legacy attribute devices
can later be also checked for with other ACPI legacy attribute
flags.
This implicates the first ACPI 5.2.9.3 IA-PC Boot Architecture
ACPI_FADT_LEGACY_DEVICES flag device, and shows how to add more.
The reason pnpbios gets a defined structure and as such uses
a different approach than the RTC legacy quirk is that ACPI
has a respective RTC flag, while pnpbios does not. We fold
the pnpbios quirk under ACPI_FADT_LEGACY_DEVICES ACPI flag
use case, and use a struct of possible devices to enable
future extensions of this.
As per 0-day, this bumps the vmlinux size using i386-tinyconfig as
follows:
TOTAL TEXT init.text x86_early_init_platform_quirks()
+32 +28 +28 +28
That's 4 byte overhead total, the rest is cleared out on init
as its all __init text.
v2: split out subarch handlng on switch to make it easier
later to add other subarchs. The 'fall-through' switch
handling can be confusing and we'll remove it later
when we add handling for X86_SUBARCH_CE4100.
v3: document vmlinux size impact as per 0-day, and also
explain why pnpbios is treated differently than the
RTC legacy feature.
Signed-off-by: Luis R. Rodriguez <mcgrof@kernel.org>
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: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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: jgross@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/1460592286-300-12-git-send-email-mcgrof@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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This replaces the paravirt_enabled() check with a
proper x86 legacy platform quirk.
As per 0-day, this bumps the vmlinux size using i386-tinyconfig as
follows:
TOTAL TEXT init.text x86_early_init_platform_quirks()
+39 +35 +35 +25
That's a 4 byte total overhead, the rest is all cleared out
upon init as its all __init text.
v2: document 0-day vmlinux size impact
Signed-off-by: Luis R. Rodriguez <mcgrof@kernel.org>
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: jgross@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/1460592286-300-7-git-send-email-mcgrof@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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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 <mingo@kernel.org>
Signed-off-by: Luis R. Rodriguez <mcgrof@kernel.org>
Reviewed-by: Juergen 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.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Ingo Molnar
Luis R. Rodriguez