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From: David Daney <ddaney.cavm@gmail.com>
To: Joshua Kinard <kumba@gentoo.org>
Cc: Ralf Baechle <ralf@linux-mips.org>,
	Linux MIPS List <linux-mips@linux-mips.org>
Subject: Re: IP27: CONFIG_TRANSPARENT_HUGEPAGE triggers bus errors
Date: Fri, 07 Nov 2014 10:30:28 -0800	[thread overview]
Message-ID: <545D0FC4.7020205@gmail.com> (raw)
In-Reply-To: <545C9D4D.4090501@gentoo.org>

On 11/07/2014 02:22 AM, Joshua Kinard wrote:
[...]
>
> So my guess is unless hugepages can happen in powers of 4,

Huge  pages are currently only supported on MIPS64 for this reason.

huge_page_mask_size = (normal_page_size/8 * normal_page_size) / 2;

If you take log2 of everything you get

huge_page_mask_bits = normal_page_bits - 3 + normal_page_bits - 1
   = 2 * normal_page_bits - 4 (always even)

So all page sizes result in huge pages that meet the power of 4 criterion.

> they're not
> compatible w/ the R10K-series (and likely not the R5K/RM7K, either, since they
> all have the same 24:13 bits in the PageMask register).  It seems the logical
> choice would be to remove 'select CPU_SUPPORTS_HUGEPAGES' from CPU_R5000,
> CPU_NEVADA, CPU_R10000, and CPU_RM7000 in arch/mips/Kconfig.
>

  reply	other threads:[~2014-11-07 18:30 UTC|newest]

Thread overview: 27+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-11-02 10:53 IP27: CONFIG_TRANSPARENT_HUGEPAGE triggers bus errors Joshua Kinard
2014-11-03 18:52 ` David Daney
2014-11-04  1:08   ` Joshua Kinard
2014-11-04  1:23     ` David Daney
2014-11-04  1:34       ` Joshua Kinard
2014-11-04  1:43         ` David Daney
2014-11-04  5:51           ` Joshua Kinard
2014-11-05  9:07       ` Joshua Kinard
2014-11-05 10:21         ` Ralf Baechle
2014-11-05 16:09       ` Ralf Baechle
2014-11-07 10:22         ` Joshua Kinard
2014-11-07 18:30           ` David Daney [this message]
2014-11-09  0:09             ` Joshua Kinard
2014-11-10  7:04               ` Joshua Kinard
2014-11-10 10:51                 ` Ralf Baechle
2014-11-10 11:20                   ` Thomas Bogendoerfer
2014-11-10 14:22                     ` Joshua Kinard
2014-11-10 16:55                       ` David Daney
2014-11-10 17:03                         ` Ralf Baechle
2014-11-10 17:29                           ` David Daney
2014-11-11 11:11                           ` Joshua Kinard
2014-11-10 21:30                     ` Thomas Bogendoerfer
2014-11-11  7:47                       ` Ralf Baechle
2014-11-11  9:24                         ` Thomas Bogendoerfer
2014-11-11  9:38                           ` Ralf Baechle
2014-11-10 11:22                   ` Joshua Kinard
2014-11-05 13:52     ` Ralf Baechle

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