linux-kernel - Re: [PATCH v15 09/10] arm64: Call kmalloc() to allocate DTB buffer

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Message-ID: <87czxjpqdd.fsf@manicouagan.localdomain>
Date:   Mon, 01 Feb 2021 15:58:06 -0300
From:   Thiago Jung Bauermann <bauerman@...ux.ibm.com>
To:     Joe Perches <joe@...ches.com>
Cc:     Will Deacon <will@...nel.org>,
        Lakshmi Ramasubramanian <nramas@...ux.microsoft.com>,
        zohar@...ux.ibm.com, robh@...nel.org, takahiro.akashi@...aro.org,
        gregkh@...uxfoundation.org, catalin.marinas@....com,
        mpe@...erman.id.au, james.morse@....com, sashal@...nel.org,
        benh@...nel.crashing.org, paulus@...ba.org, frowand.list@...il.com,
        vincenzo.frascino@....com, mark.rutland@....com,
        dmitry.kasatkin@...il.com, jmorris@...ei.org, serge@...lyn.com,
        pasha.tatashin@...een.com, allison@...utok.net,
        masahiroy@...nel.org, bhsharma@...hat.com, mbrugger@...e.com,
        hsinyi@...omium.org, tao.li@...o.com, christophe.leroy@....fr,
        prsriva@...ux.microsoft.com, balajib@...ux.microsoft.com,
        linux-integrity@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, devicetree@...r.kernel.org,
        linuxppc-dev@...ts.ozlabs.org
Subject: Re: [PATCH v15 09/10] arm64: Call kmalloc() to allocate DTB buffer


Joe Perches <joe@...ches.com> writes:

> On Thu, 2021-01-28 at 00:52 -0300, Thiago Jung Bauermann wrote:
>> The problem is that this patch implements only part of the suggestion,
>> which isn't useful in itself. So the patch series should either drop
>> this patch or consolidate the FDT allocation between the arches.
>> 
>> I just tested on powernv and pseries platforms and powerpc can use
>> vmalloc for the FDT buffer.
>
> Perhaps more sensible to use kvmalloc/kvfree.

That's true. Converting both arm64 to powerpc to kvmalloc/kvfree is a
good option. I don't think it's that much better though, because
kexec_file_load() is called infrequently and doesn't need to be fast so
the vmalloc() overhead isn't important in practice.

-- 
Thiago Jung Bauermann
IBM Linux Technology Center