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From: Geert Uytterhoeven <geert@linux-m68k.org>
To: Robin Murphy <robin.murphy@arm.com>
Cc: Eric Dumazet <edumazet@google.com>,
	Christoph Hellwig <hch@lst.de>, Joerg Roedel <jroedel@suse.de>,
	Linux IOMMU <iommu@lists.linux-foundation.org>,
	Eric Dumazet <eric.dumazet@gmail.com>,
	linux-kernel <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] dma-debug: dynamic allocation of hash table
Date: Fri, 31 Jan 2020 10:06:47 +0100	[thread overview]
Message-ID: <CAMuHMdVSyD62nvRmN-v6CbJ2UyqH=d7xdVeCD8_X5us+mvCXUQ@mail.gmail.com> (raw)
In-Reply-To: <e0a0ffa9-3721-4bac-1c8f-bcbd53d22ba1@arm.com>

Hi Robin,

On Fri, Jan 31, 2020 at 12:46 AM Robin Murphy <robin.murphy@arm.com> wrote:
> On 2020-01-30 7:10 pm, Eric Dumazet via iommu wrote:
> > Increasing the size of dma_entry_hash size by 327680 bytes
> > has reached some bootloaders limitations.
>
> [ That might warrant some further explanation - I don't quite follow how
> this would relate to a bootloader specifically :/ ]

Increasing the size of a static array increases kernel size.
Some (all? ;-) bootloaders have limitations on the maximum size of a
kernel image they can boot (usually something critical gets overwritten
when handling a too large image).  While boot loaders can be fixed and
upgraded, this is usually much more cumbersome than updating the
kernel.

Besides, a static array always consumes valuable unswapable memory,
even when the feature would not be used (e.g. disabled by a command
line option).

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds

  parent reply	other threads:[~2020-01-31  9:07 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-01-30 19:10 [PATCH] dma-debug: dynamic allocation of hash table Eric Dumazet
2020-01-30 23:46 ` Robin Murphy
2020-01-31  0:17   ` Eric Dumazet
2020-01-31 12:30     ` Robin Murphy
2020-01-31 14:42       ` Eric Dumazet
2020-01-31 17:43         ` Robin Murphy
2020-01-31 17:46           ` Eric Dumazet
2020-02-01  0:06             ` Robin Murphy
2020-01-31  9:06   ` Geert Uytterhoeven [this message]
2020-01-31 11:33     ` Robin Murphy

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