Messages in this thread Patch in this message | | | Date | Mon, 25 Apr 2011 23:25:02 GMT | From | "tip-bot for H. Peter Anvin" <> | Subject | [tip:x86/urgent] x86, setup: When probing memory with e801, use ax/bx as a pair |
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Commit-ID: 39b68976ac653cfdc7f872a293e8b7928de2dcc6 Gitweb: http://git.kernel.org/tip/39b68976ac653cfdc7f872a293e8b7928de2dcc6 Author: H. Peter Anvin <hpa@linux.intel.com> AuthorDate: Mon, 25 Apr 2011 14:52:37 -0700 Committer: H. Peter Anvin <hpa@linux.intel.com> CommitDate: Mon, 25 Apr 2011 14:52:37 -0700
x86, setup: When probing memory with e801, use ax/bx as a pair
When we use BIOS function e801 to probe memory, we should use ax/bx (or cx/dx) as a pair, not mix and match. This was a typo during the translation from assembly code, and breaks at least one set of machines in the field (which return cx = dx = 0).
Reported-and-tested-by: Chris Samuel <chris@csamuel.org> Fix-proposed-by: Thomas Meyer <thomas@m3y3r.de> Link: http://lkml.kernel.org/r/1303566747.12067.10.camel@localhost.localdomain --- arch/x86/boot/memory.c | 2 +- 1 files changed, 1 insertions(+), 1 deletions(-)
diff --git a/arch/x86/boot/memory.c b/arch/x86/boot/memory.c index cae3feb..db75d07 100644 --- a/arch/x86/boot/memory.c +++ b/arch/x86/boot/memory.c @@ -91,7 +91,7 @@ static int detect_memory_e801(void) if (oreg.ax > 15*1024) { return -1; /* Bogus! */ } else if (oreg.ax == 15*1024) { - boot_params.alt_mem_k = (oreg.dx << 6) + oreg.ax; + boot_params.alt_mem_k = (oreg.bx << 6) + oreg.ax; } else { /* * This ignores memory above 16MB if we have a memory
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