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Re: [Qemu-devel] [PATCH v4] Add optionrom compatible with fw_cfg DMA ver
From: |
Gerd Hoffmann |
Subject: |
Re: [Qemu-devel] [PATCH v4] Add optionrom compatible with fw_cfg DMA version |
Date: |
Wed, 03 Feb 2016 09:44:35 +0100 |
Hi,
> I think the "dma_enabled" property is not exposed to the user.
It is: "-global fw_cfg.dma_enabled=off" works (as in: doesn't throw an
error). Has no effect through as it gets overridden later on.
> The default value of "dma_enabled" in both fw_cfg_io_properties and
> fw_cfg_mem_properties is irrelevant; the actual property value is always
> overwritten in fw_cfg_init_io_dma() and fw_cfg_init_mem_wide(), which
> all of the init paths go through.
And IMHO we should not do that, so setting the property actually has an
effect.
> I agree that DMA capability should be filtered with machine type.
> However, that distinction should not be made using the current
> "dma_enabled" properties (i.e., of "fw_cfg_io_properties" and
> "fw_cfg_mem_properties". Instead, it should be made in the
> board-specific callers of fw_cfg_init_(io_dma|mem_wide).
Why?
cheers,
Gerd
Re: [Qemu-devel] [PATCH v4] Add optionrom compatible with fw_cfg DMA version, Marc MarĂ, 2016/02/02