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Re: [Qemu-devel] [RFC v1] Add declarations for hierarchical memory regio


From: Avi Kivity
Subject: Re: [Qemu-devel] [RFC v1] Add declarations for hierarchical memory region API
Date: Fri, 20 May 2011 12:18:58 +0300
User-agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.2.17) Gecko/20110428 Fedora/3.1.10-1.fc14 Thunderbird/3.1.10

On 05/19/2011 10:07 PM, Alex Williamson wrote:
On Thu, 2011-05-19 at 10:12 -0400, Avi Kivity wrote:
>  The memory API separates the attributes of a memory region (its size, how
>  reads or writes are handled, dirty logging, and coalescing) from where it
>  is mapped and whether it is enabled.  This allows a device to configure
>  a memory region once, then hand it off to its parent bus to map it according
>  to the bus configuration.
>
>  Hierarchical registration also allows a device to compose a region out of
>  a number of sub-regions with different properties; for example some may be
>  RAM while others may be MMIO.

>  +    /* Guest-visible constraints: */
>  +    struct {
>  +        /* If nonzero, specify bounds on access sizes beyond which a machine
>  +         * check is thrown.
>  +         */
>  +        unsigned min_access_size;
>  +        unsigned max_access_size;

Do we always support all access sizes between min and max?

As far as I can tell, yes.

This might
be easier to describe as a bitmap of supported power of 2 access sizes.

This is uglier to initialize. However we can provide #defines for common use (MEM_ACCESS_BYTE_TO_LONG, MEM_ACCESS_LONG).

--
I have a truly marvellous patch that fixes the bug which this
signature is too narrow to contain.




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