> -----Original Message----- > From: Thomas Gleixner [mailto:tglx@xxxxxxxxxxxxx] > Sent: Friday, May 06, 2016 5:53 PM > To: Chen, Yu C > Cc: x86@xxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; Ingo Molnar; H. Peter Anvin; > Gao, Bin; Len Brown; Rafael J. Wysocki; 3 . 14+ # 3 . 14+ > Subject: Re: [PATCH] x86, tsc: Fix tsc ratio calibration to avoid broken mdelay > > > On Fri, 6 May 2016, Thomas Gleixner wrote: > > On Fri, 6 May 2016, yu.c.chen@xxxxxxxxx wrote: > > > From: Chen Yu <yu.c.chen@xxxxxxxxx> > > > > > > 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@xxxxxxxxxxxxxxx> # 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. > OK, thanks! -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html