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由 Paul Mackerras 提交于
On the old "powersurge" SMP powermacs, the second CPU is started up by sending it an IPI, which has the side effect of stopping the timebase clock (so the secondary CPU's timebase can be synchronized with the primary's). The routine that did this used udelay, which will hang forever when the timebase is stopped, since udelay now spins until the timebase reaches a certain value. The end result is that the kernel would hang when bringing up the second CPU. This fixes it by using a simple loop which just does a fixed number of iterations to generate the delay. These old systems were all clocked at around 200 MHz or so, so a fixed number of iterations is acceptable. Signed-off-by: NPaul Mackerras <paulus@samba.org>
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