From: Christophe Leroy <christophe.leroy@csgroup.eu>
To: "Jason A. Donenfeld" <Jason@zx2c4.com>
Cc: "linuxppc-dev@lists.ozlabs.org" <linuxppc-dev@lists.ozlabs.org>,
LKML <linux-kernel@vger.kernel.org>,
stable <stable@vger.kernel.org>
Subject: Re: [PATCH v5] powerpc/powernv: wire up rng during setup_arch
Date: Tue, 21 Jun 2022 19:22:56 +0000 [thread overview]
Message-ID: <a354de5e-1d07-3759-a55e-a9179890cfaa@csgroup.eu> (raw)
In-Reply-To: <YrISWLwm8m7OPFom@zx2c4.com>
Le 21/06/2022 à 20:47, Jason A. Donenfeld a écrit :
> Hi Christophe,
>
> On Tue, Jun 21, 2022 at 06:33:11PM +0000, Christophe Leroy wrote:
>> Le 21/06/2022 à 16:08, Jason A. Donenfeld a écrit :
>>> The platform's RNG must be available before random_init() in order to be
>>> useful for initial seeding, which in turn means that it needs to be
>>> called from setup_arch(), rather than from an init call. Fortunately,
>>> each platform already has a setup_arch function pointer, which means we
>>> can wire it up that way. Complicating things, however, is that POWER8
>>> systems need some per-cpu state and kmalloc, which isn't available at
>>> this stage. So we split things up into an early phase and a later
>>> opportunistic phase. This commit also removes some noisy log messages
>>> that don't add much.
>>
>> Regarding the kmalloc(), I have not looked at it in details, but usually
>> you can use memblock_alloc() when kmalloc is not available yet.
>
> That seems a bit excessive, especially as those allocations are long
> lived. And we don't even *need* it that early, but just before
> random_init(). Michael is running this v5 on the test rig overnight, so
> we'll learn in the Australian morning whether this finally did the trick
> (I hope).
>
The fact that they are long lived make them a good candidate for
memblock_alloc().
But fair enough, if they are not required that early then just do it later.
Christophe
next prev parent reply other threads:[~2022-06-21 19:24 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-06-11 15:10 [PATCH v3 0/3] powerpc: wire up rng during setup_arch Jason A. Donenfeld
2022-06-11 15:10 ` [PATCH v3 1/3] powerpc/microwatt: " Jason A. Donenfeld
2022-06-11 16:25 ` Christophe Leroy
2022-06-11 15:10 ` [PATCH v3 2/3] powerpc/powernv: " Jason A. Donenfeld
2022-06-11 16:25 ` Christophe Leroy
2022-06-19 11:49 ` Michael Ellerman
2022-06-19 20:32 ` Jason A. Donenfeld
2022-06-20 12:45 ` [PATCH v4] " Jason A. Donenfeld
2022-06-21 14:08 ` [PATCH v5] " Jason A. Donenfeld
2022-06-21 18:33 ` Christophe Leroy
2022-06-21 18:47 ` Jason A. Donenfeld
2022-06-21 19:22 ` Christophe Leroy [this message]
2022-06-22 2:27 ` Michael Ellerman
2022-06-26 0:28 ` Michael Ellerman
2022-06-11 15:10 ` [PATCH v3 3/3] powerpc/pseries: " Jason A. Donenfeld
2022-06-11 16:25 ` Christophe Leroy
2022-06-19 11:55 ` [PATCH v3 0/3] powerpc: " Michael Ellerman
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