Messages in this thread | | | Date | Fri, 6 May 2016 11:53:25 +0200 (CEST) | From | Thomas Gleixner <> | Subject | Re: [PATCH] x86, tsc: Fix tsc ratio calibration to avoid broken mdelay |
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On Fri, 6 May 2016, Thomas Gleixner wrote: > On Fri, 6 May 2016, yu.c.chen@intel.com wrote: > > From: Chen Yu <yu.c.chen@intel.com> > > > > Currently we fetch the tsc radio by: > > ratio = (lo >> 8) & 0x1f; > > thus get bit8~bit12 of the MSR_PLATFORM_INFO, however according > > to Intel 64 and IA-32 Architectures Software Developer Manual 35.5, > > the ratio bit should be bit8~bit15, otherwise we might get incorrect > > tsc ratio and cause system hang later(mdelay corrupted). > > The resulting issue is that both TSC frequency, which is used for udelay, and > the lapic timer frequency are wrong. mdelay is just the visible damage caused > by that.
Aside of that:
> Cc: 3.14+ <stable@vger.kernel.org> # 3.14+
Please use:
Fixes: commit '....'
next time, which identifies the kernel version to which this needs to be backported and gives a reference to the commit which caused the issue.
Thanks,
tglx
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