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Message-ID: <62dc4371-d971-9164-1c1d-8923877b5e31@infradead.org> Date: Mon, 8 Feb 2021 16:55:03 -0800 From: Randy Dunlap <rdunlap@...radead.org> To: Florian Fainelli <f.fainelli@...il.com>, linux-kernel@...r.kernel.org, corbet@....net Cc: "Paul E. McKenney" <paulmck@...nel.org>, Andrew Morton <akpm@...ux-foundation.org>, Thomas Gleixner <tglx@...utronix.de>, Mauro Carvalho Chehab <mchehab+huawei@...nel.org>, Mike Kravetz <mike.kravetz@...cle.com>, "Guilherme G. Piccoli" <gpiccoli@...onical.com>, "open list:DOCUMENTATION" <linux-doc@...r.kernel.org> Subject: Re: [PATCH] Documentation/admin-guide: kernel-parameters: Update nohlt section On 2/8/21 4:30 PM, Florian Fainelli wrote: > Update the documentation regarding "nohlt" and indicate that it is not > only for bugs, but can be useful to disable the architecture specific > sleep instructions. ARM, ARM64, SuperH and Microblaze all use > CONFIG_GENERIC_IDLE_POLL_SETUP which takes care of honoring the > "hlt"/"nohlt" parameters. > > Signed-off-by: Florian Fainelli <f.fainelli@...il.com> > --- > Documentation/admin-guide/kernel-parameters.txt | 11 ++++++++--- > 1 file changed, 8 insertions(+), 3 deletions(-) > > diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt > index a10b545c2070..83c37e23e1e2 100644 > --- a/Documentation/admin-guide/kernel-parameters.txt > +++ b/Documentation/admin-guide/kernel-parameters.txt > @@ -3266,9 +3266,14 @@ > parameter, xsave area per process might occupy more > memory on xsaves enabled systems. > > - nohlt [BUGS=ARM,SH] Tells the kernel that the sleep(SH) or > - wfi(ARM) instruction doesn't work correctly and not to > - use it. This is also useful when using JTAG debugger. > + nohlt [ARM,ARM64,MICROBLAZE,SH] Forces the kernel to busy wait > + in do_idle() and not use the arch_cpu_idle() > + implementation, requires CONFIG_GENERIC_IDLE_POLL_SETUP Sounds good... but above, I would prefer s/,/;/ > + to be effective. This is useful on platforms where the > + sleep(SH) or wfi(ARM,ARM64) instructions do not work > + correctly or when doing power measurements to evalute > + the impact of the sleep instructions. This is also > + useful when using JTAG debugger. > > no_file_caps Tells the kernel not to honor file capabilities. The > only way then for a file to be executed with privilege > Acked-by: Randy Dunlap <rdunlap@...radead.org> thanks. -- ~Randy
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