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From: Segher Boessenkool <segher@kernel.crashing.org>
To: Michael Ellerman <mpe@ellerman.id.au>
Cc: linux-arch@vger.kernel.org, robh@kernel.org,
	daniel@gimpelevich.san-francisco.ca.us,
	devicetree@vger.kernel.org, linuxppc-dev@lists.ozlabs.org,
	linux-kernel@vger.kernel.org, Paul Mackerras <paulus@samba.org>,
	Will Deacon <will@kernel.org>,
	danielwa@cisco.com
Subject: Re: [PATCH v2 1/7] cmdline: Add generic function to build command line.
Date: Fri, 5 Mar 2021 12:33:00 -0600	[thread overview]
Message-ID: <20210305183300.GX29191@gate.crashing.org> (raw)
In-Reply-To: <87sg59rewl.fsf@mpe.ellerman.id.au>

On Fri, Mar 05, 2021 at 10:58:02PM +1100, Michael Ellerman wrote:
> Will Deacon <will@kernel.org> writes:
> > That's very similar to us; we're not relocated, although we are at least
> > in control of the MMU (which is using a temporary set of page-tables).
> 
> prom_init runs as an OF client, with the MMU off (except on some Apple
> machines), and we don't own the MMU. So there's really nothing we can do :)

You *could* take over all memory mapping.  This is complex, and I
estimate the change you get this to work correctly on all supported
systems to be between -400% and 0%.

And not very long later Linux jettisons OF completely anyway.

> Though now that I look at it, I don't think we should be doing this
> level of commandline handling in prom_init. It should just grab the
> value from firmware and pass it to the kernel proper, and then all the
> prepend/append/force etc. logic should happen there.

That sounds much simpler, yes :-)


Segher

  parent reply	other threads:[~2021-03-05 18:37 UTC|newest]

Thread overview: 31+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-03-02 17:25 [PATCH v2 0/7] Improve boot command line handling Christophe Leroy
2021-03-02 17:25 ` [PATCH v2 1/7] cmdline: Add generic function to build command line Christophe Leroy
2021-03-03 17:28   ` Will Deacon
2021-03-03 17:38     ` Christophe Leroy
2021-03-03 17:46       ` Will Deacon
2021-03-03 17:57         ` Christophe Leroy
2021-03-03 18:16           ` Will Deacon
2021-03-05 11:58             ` Michael Ellerman
2021-03-05 12:49               ` Christophe Leroy
2021-03-05 18:35                 ` Segher Boessenkool
2021-03-05 18:33               ` Segher Boessenkool [this message]
2021-03-03 17:39   ` Will Deacon
2021-03-02 17:25 ` [PATCH v2 2/7] drivers: of: use cmdline building function Christophe Leroy
2021-03-02 17:25 ` [PATCH v2 3/7] powerpc: convert to generic builtin command line Christophe Leroy
2021-03-02 17:25 ` [PATCH v2 4/7] cmdline: Add capability to prepend the " Christophe Leroy
2021-03-03 18:19   ` Will Deacon
2021-03-02 17:25 ` [PATCH v2 5/7] powerpc: add capability to prepend default " Christophe Leroy
2021-03-02 17:25 ` [PATCH v2 6/7] cmdline: Gives architectures opportunity to use generically defined boot cmdline manipulation Christophe Leroy
2021-03-02 19:30   ` kernel test robot
2021-03-03 17:57   ` Will Deacon
2021-03-25 11:18     ` Christophe Leroy
2021-03-25 19:32       ` Will Deacon
2021-03-26  6:18         ` Christophe Leroy
2021-03-26  6:44     ` Christophe Leroy
2021-03-02 17:25 ` [PATCH v2 7/7] powerpc: use generic CMDLINE manipulations Christophe Leroy
2021-03-02 17:35 ` [PATCH v2 0/7] Improve boot command line handling Daniel Walker
2021-03-02 17:39   ` Christophe Leroy
2021-03-03  2:01   ` Rob Herring
2021-03-03 17:39     ` Daniel Walker
2021-03-03 18:07       ` Christophe Leroy
2021-03-03 18:53         ` Daniel Walker

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