From: Paul Brook <paul@codesourcery.com>
To: qemu-devel@nongnu.org
Cc: "Richard W.M. Jones" <rjones@redhat.com>
Subject: Re: [Qemu-devel] [PATCH REPOST] fw_cfg: Allow guest to read kernel etc via fast, synchronous "DMA"-type operation.
Date: Thu, 25 Nov 2010 17:52:49 +0000 [thread overview]
Message-ID: <201011251752.49551.paul@codesourcery.com> (raw)
In-Reply-To: <20100803144931.GE22211@amd.home.annexia.org>
> I rebased this and rechecked it. The *total* libguestfs boot time
> goes from 86 seconds down to 7.7 seconds. The proportion of that
> attributable to loading the appliance is approximately 650 times [sic]
> faster.
Nack.
> +/* Target address and size for DMA operations. This is only used
> + * during boot and across 32 and 64 bit architectures, so only writes
> + * to lower 4GB addresses are supported.
> + */
> +static uint32_t dma_addr = 0;
> +static uint32_t dma_size = 0;
Storing per-device state in global variables is just plain wrong.
Limiting addresses to 32-bits is just lame. You can do better.
It's also completely broken on big-endian hosts.
Paul
prev parent reply other threads:[~2010-11-25 17:53 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-08-03 14:49 [Qemu-devel] [PATCH REPOST] fw_cfg: Allow guest to read kernel etc via fast, synchronous "DMA"-type operation Richard W.M. Jones
2010-11-25 17:52 ` Paul Brook [this message]
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