SVNews r179825

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2008-06-16 17:04:04 - r179825 by olli (Oliver Fromme)

Complete list of files affected by revision r179825:

(Note: At the moment, these links point to ViewVC on svn.freebsd.org. They are probably slow. Do not overuse.)

History Contents Diff MODIFY /head/sys/boot/i386/libi386/time.c

Commit message:

Implement a workaround for a long-standing problem in

libi386's time(), caused by a qemu bug.  The bug might

be present in other BIOSes, too.



qemu either does not simulate the AT RTC correctly or

has a broken BIOS 1A/02 implementation, and will return

an incorrect value if the RTC is read while it is being

updated.



The effect is worsened by the fact that qemu's INT 15/86

function ("wait" a.k.a. usleep) is non-implmeneted or

broken and returns immediately, causing beastie.4th to

spin in a tight loop calling the "read RTC" function

millions of times, triggering the problem quickly.



Therefore, we keep reading the BIOS value until we get

the same result twice.  This change fixes beastie.4th's

countdown under qemu.



Approved by:    des (mentor)

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