From: Michael Ellerman <mpe@ellerman.id.au>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: David Hildenbrand <david@redhat.com>,
Catalin Marinas <catalin.marinas@arm.com>,
Yang Shi <shy828301@gmail.com>,
linux-kernel@vger.kernel.org, linux-mm@kvack.org,
Yu Zhao <yuzhao@google.com>,
"Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com>,
Hugh Dickins <hughd@google.com>,
Matthew Wilcox <willy@infradead.org>,
Vlastimil Babka <vbabka@suse.cz>, Zi Yan <ziy@nvidia.com>,
"Huang, Ying" <ying.huang@intel.com>,
Ryan Roberts <ryan.roberts@arm.com>,
Anshuman Khandual <anshuman.khandual@arm.com>,
John Hubbard <jhubbard@nvidia.com>,
David Rientjes <rientjes@google.com>,
Itaru Kitayama <itaru.kitayama@gmail.com>,
linux-arm-kernel@lists.infradead.org,
Yin Fengwei <fengwei.yin@intel.com>,
Luis Chamberlain <mcgrof@kernel.org>,
linuxppc-dev@lists.ozlabs.org,
"Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Subject: Re: [PATCH v6 4/9] mm: thp: Introduce anon_orders and anon_always_mask sysfs files
Date: Thu, 12 Oct 2023 22:07:26 +1100 [thread overview]
Message-ID: <87o7h4qett.fsf@mail.lhotse> (raw)
In-Reply-To: <20231009172029.e558c08dd90d9b94fec3a036@linux-foundation.org>
Andrew Morton <akpm@linux-foundation.org> writes:
> On Sun, 08 Oct 2023 09:54:22 +1100 Michael Ellerman <mpe@ellerman.id.au> wrote:
>
>> > I don't know why powerpc's PTE_INDEX_SIZE is variable.
>>
>> To allow a single vmlinux to boot using either the Hashed Page Table
>> MMU, or Radix Tree MMU, which have different page table geometry.
>>
>> That's a pretty crucial feature for distros, so that they can build a
>> single kernel to boot on Power8/9/10.
>
> Dumb question: why can't distros ship two kernels and have the boot
> loader (or something else) pick the appropriate one?
I'm not a grub expert, but AFAIK it doesn't support loading a different
kernel based on CPU/firwmare features. I'm quite sure it can't do that
on powerpc at least.
We also have another bootloader (petitboot) that is still supported by
some distros, and can't do that.
The other problem is like David says, distros are generally reluctant to
add new kernel configurations unless they absolutely have to. It adds
more work for them, more things to track, and can confuse users leading
to spurious bug reports.
cheers
prev parent reply other threads:[~2023-10-12 11:08 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20230929114421.3761121-1-ryan.roberts@arm.com>
[not found] ` <20230929114421.3761121-5-ryan.roberts@arm.com>
2023-09-29 22:55 ` [PATCH v6 4/9] mm: thp: Introduce anon_orders and anon_always_mask sysfs files Andrew Morton
2023-10-02 10:15 ` Ryan Roberts
2023-10-07 22:54 ` Michael Ellerman
2023-10-10 0:20 ` Andrew Morton
2023-10-12 9:31 ` David Hildenbrand
2023-10-12 11:07 ` Michael Ellerman [this message]
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