Re: [Qemu-devel] Question about qemu firmware configuration (fw_cfg) device

[Richard W.M. Jones]

On Mon, Jul 19, 2010 at 07:11:37PM +0300, Gleb Natapov wrote:
> And there are such that cause cpu to stall for 6.5 seconds when you do
> io to them? I never said that we should implement ISA or PCI device, I
> don't know why you bring them here.

Where is "6.5 seconds" coming from?  That is the *total boot time*
of the libguestfs appliance, and includes far far more than the
time taken to do the memcpy.

I timed the call to cpu_physical_memory_write, and it takes 115
milliseconds with my patch (for an initrd which is 113 MB).

> It should look like real DMA at least. The justification for it should
> be better than "In our project we don't what to do this and we don't
> what to do that so our initrd is 100M now, so why not add hack to qemu
> to load it 1 second faster so we can grow it some more".

Please don't make stuff up.  We have a large initrd for perfectly good
reasons which I have outlined in a previous email.

Rich.

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