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author | Luis R. Rodriguez <mcgrof@kernel.org> | 2016-04-13 17:04:43 -0700 |
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committer | Ingo Molnar <mingo@kernel.org> | 2016-04-22 10:29:07 +0200 |
commit | f2d85299b7f11f73cc0a294e396cdae114e75787 (patch) | |
tree | 34f0cf3187dff89ae833c376b534f5d5807487f5 /arch/x86/kernel/ebda.c | |
parent | 7a17b82ccd6671a4bb436df52eedeff906b02735 (diff) | |
download | op-kernel-dev-f2d85299b7f11f73cc0a294e396cdae114e75787.zip op-kernel-dev-f2d85299b7f11f73cc0a294e396cdae114e75787.tar.gz |
x86/init: Rename EBDA code file
This makes it clearer what this is.
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/1460592286-300-14-git-send-email-mcgrof@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'arch/x86/kernel/ebda.c')
-rw-r--r-- | arch/x86/kernel/ebda.c | 71 |
1 files changed, 71 insertions, 0 deletions
diff --git a/arch/x86/kernel/ebda.c b/arch/x86/kernel/ebda.c new file mode 100644 index 0000000..afe65df --- /dev/null +++ b/arch/x86/kernel/ebda.c @@ -0,0 +1,71 @@ +#include <linux/kernel.h> +#include <linux/init.h> +#include <linux/memblock.h> + +#include <asm/setup.h> +#include <asm/bios_ebda.h> + +/* + * The BIOS places the EBDA/XBDA at the top of conventional + * memory, and usually decreases the reported amount of + * conventional memory (int 0x12) too. This also contains a + * workaround for Dell systems that neglect to reserve EBDA. + * The same workaround also avoids a problem with the AMD768MPX + * chipset: reserve a page before VGA to prevent PCI prefetch + * into it (errata #56). Usually the page is reserved anyways, + * unless you have no PS/2 mouse plugged in. + * + * This functions is deliberately very conservative. Losing + * memory in the bottom megabyte is rarely a problem, as long + * as we have enough memory to install the trampoline. Using + * memory that is in use by the BIOS or by some DMA device + * the BIOS didn't shut down *is* a big problem. + */ + +#define BIOS_LOWMEM_KILOBYTES 0x413 +#define LOWMEM_CAP 0x9f000U /* Absolute maximum */ +#define INSANE_CUTOFF 0x20000U /* Less than this = insane */ + +void __init reserve_ebda_region(void) +{ + unsigned int lowmem, ebda_addr; + + /* + * To determine the position of the EBDA and the + * end of conventional memory, we need to look at + * the BIOS data area. In a paravirtual environment + * that area is absent. We'll just have to assume + * that the paravirt case can handle memory setup + * correctly, without our help. + */ + if (!x86_platform.legacy.ebda_search) + return; + + /* end of low (conventional) memory */ + lowmem = *(unsigned short *)__va(BIOS_LOWMEM_KILOBYTES); + lowmem <<= 10; + + /* start of EBDA area */ + ebda_addr = get_bios_ebda(); + + /* + * Note: some old Dells seem to need 4k EBDA without + * reporting so, so just consider the memory above 0x9f000 + * to be off limits (bugzilla 2990). + */ + + /* If the EBDA address is below 128K, assume it is bogus */ + if (ebda_addr < INSANE_CUTOFF) + ebda_addr = LOWMEM_CAP; + + /* If lowmem is less than 128K, assume it is bogus */ + if (lowmem < INSANE_CUTOFF) + lowmem = LOWMEM_CAP; + + /* Use the lower of the lowmem and EBDA markers as the cutoff */ + lowmem = min(lowmem, ebda_addr); + lowmem = min(lowmem, LOWMEM_CAP); /* Absolute cap */ + + /* reserve all memory between lowmem and the 1MB mark */ + memblock_reserve(lowmem, 0x100000 - lowmem); +} |