Commit-ID: 1330e3bc544a1951d81b7f3c7d4cecf77d906f67
Gitweb: http://git.kernel.org/tip/1330e3bc544a1951d81b7f3c7d4cecf77d906f67
Author: Luis R. Rodriguez <mcgrof@xxxxxxxxxx>
AuthorDate: Wed, 13 Apr 2016 17:04:36 -0700
Committer: Ingo Molnar <mingo@xxxxxxxxxx>
CommitDate: Fri, 22 Apr 2016 10:29:02 +0200
x86/init: Use a platform legacy quirk for EBDA
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@xxxxxxxxxx>
Cc: Andy Lutomirski <luto@xxxxxxxxxxxxxx>
Cc: Borislav Petkov <bp@xxxxxxxxx>
Cc: Brian Gerst <brgerst@xxxxxxxxx>
Cc: Denys Vlasenko <dvlasenk@xxxxxxxxxx>
Cc: H. Peter Anvin <hpa@xxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: andrew.cooper3@xxxxxxxxxx
Cc: andriy.shevchenko@xxxxxxxxxxxxxxx
Cc: bigeasy@xxxxxxxxxxxxx
Cc: boris.ostrovsky@xxxxxxxxxx
Cc: david.vrabel@xxxxxxxxxx
Cc: ffainelli@xxxxxxxxxx
Cc: george.dunlap@xxxxxxxxxx
Cc: glin@xxxxxxxx
Cc: jgross@xxxxxxxx
Cc: jlee@xxxxxxxx
Cc: josh@xxxxxxxxxxxxxxxx
Cc: julien.grall@xxxxxxxxxx
Cc: konrad.wilk@xxxxxxxxxx
Cc: kozerkov@xxxxxxxxxxxxx
Cc: lenb@xxxxxxxxxx
Cc: lguest@xxxxxxxxxxxxxxxx
Cc: linux-acpi@xxxxxxxxxxxxxxx
Cc: lv.zheng@xxxxxxxxx
Cc: matt@xxxxxxxxxxxxxxxxxxx
Cc: mbizon@xxxxxxxxxx
Cc: rjw@xxxxxxxxxxxxx
Cc: robert.moore@xxxxxxxxx
Cc: rusty@xxxxxxxxxxxxxxx
Cc: tiwai@xxxxxxx
Cc: toshi.kani@xxxxxx
Cc: xen-devel@xxxxxxxxxxxxxxxxxxx
Link: http://lkml.kernel.org/r/1460592286-300-7-git-send-email-mcgrof@xxxxxxxxxx
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
---
arch/x86/include/asm/x86_init.h | 3 +++
arch/x86/kernel/head.c | 2 +-
arch/x86/kernel/platform-quirks.c | 4 ++++
3 files changed, 8 insertions(+), 1 deletion(-)
diff --git a/arch/x86/include/asm/x86_init.h b/arch/x86/include/asm/x86_init.h
index 8bb8c1a..89d9d57 100644
--- a/arch/x86/include/asm/x86_init.h
+++ b/arch/x86/include/asm/x86_init.h
@@ -145,9 +145,12 @@ struct timespec;
* struct x86_legacy_features - legacy x86 features
*
* @rtc: this device has a CMOS real-time clock present
+ * @ebda_search: it's safe to search for the EBDA signature in the hardware's
+ * low RAM
*/
struct x86_legacy_features {
int rtc;
+ int ebda_search;
};
/**
diff --git a/arch/x86/kernel/head.c b/arch/x86/kernel/head.c
index 992f442..afe65df 100644
--- a/arch/x86/kernel/head.c
+++ b/arch/x86/kernel/head.c
@@ -38,7 +38,7 @@ void __init reserve_ebda_region(void)
* that the paravirt case can handle memory setup
* correctly, without our help.
*/
- if (paravirt_enabled())
+ if (!x86_platform.legacy.ebda_search)
return;
/* end of low (conventional) memory */
diff --git a/arch/x86/kernel/platform-quirks.c b/arch/x86/kernel/platform-quirks.c
index 021a5f9..01b1597 100644
--- a/arch/x86/kernel/platform-quirks.c
+++ b/arch/x86/kernel/platform-quirks.c
@@ -7,8 +7,12 @@
void __init x86_early_init_platform_quirks(void)
{
x86_platform.legacy.rtc = 1;
+ x86_platform.legacy.ebda_search = 0;
switch (boot_params.hdr.hardware_subarch) {
+ case X86_SUBARCH_PC:
+ x86_platform.legacy.ebda_search = 1;
+ break;
case X86_SUBARCH_XEN:
case X86_SUBARCH_LGUEST:
case X86_SUBARCH_INTEL_MID:
--
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