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From: | Anthony Liguori |
Subject: | Re: [Qemu-devel] Slow kernel/initrd loading via fw_cfg; Was Re: Hack integrating SeaBios / LinuxBoot option rom with QEMU trace backends |
Date: | Tue, 11 Oct 2011 08:29:13 -0500 |
User-agent: | Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.2.21) Gecko/20110831 Lightning/1.0b2 Thunderbird/3.1.13 |
On 10/11/2011 08:23 AM, Avi Kivity wrote:
On 10/11/2011 03:19 PM, Anthony Liguori wrote:No, DMA has a lot bigger granularities in kvm/user interaction. We can easily DMA a 50MB region with a single kvm/user exit. For PIO we can at most do page granularity.So make a proper PCI device for kernel loading. It's a much more natural approach and let's use alias -kernel/-initrd/-append to -device kernel-pci,kernel=PATH,initrd=PATHThis is overkill. First let's optimize rep/movs before introducing any more interfaces. If that doesn't work, then we can have a dma interface for fwcfg. But a new pci device?
This is how it would work on bare metal. Why is a PCI device overkill compared to a dma interface for fwcfg?
If we're adding dma to fwcfg, then fwcfg has become far too complex for it's intended purpose.
Regards, Anthony Liguori
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