Date: Fri, 28 Jan 2000 16:35:37 -0700 From: Warner Losh <imp@village.org> To: Doug Rabson <dfr@nlsystems.com> Cc: YAMAMOTO Shigeru <shigeru@iij.ad.jp>, freebsd-hackers@FreeBSD.ORG Subject: Re: how to allocate an alined address for a device? Message-ID: <200001282335.QAA65386@harmony.village.org> In-Reply-To: Your message of "Fri, 28 Jan 2000 10:28:44 GMT." <Pine.BSF.4.10.10001281024320.25770-100000@salmon.nlsystems.com> References: <Pine.BSF.4.10.10001281024320.25770-100000@salmon.nlsystems.com>
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In message <Pine.BSF.4.10.10001281024320.25770-100000@salmon.nlsystems.com> Doug Rabson writes: : I'm uneasy about using the flags for this since I'm vaguely reserving the : upper 16 bits of flags for bus-specific purposes (although I haven't : formalised this). : : For allocating aligned regions with pnp, I simply looped in the caller : trying each specific range until one was free (see isa_find_port() in : isa_common.c). This is ugly but it does work. : : In the long run, I think we need either an extra parameter to : rman_reserve_resource() or a new api rman_reserve_resource_aligned(). : This also implies changing the method BUS_ALLOC_RESOURCE() or adding : BUS_ALLOC_RESOURCE_ALIGNED(). Well, with just 6 bits one could handle any alignment requirement up to 2^(2^6). We have 6 bits left. If this were the alignment requirement, a value of 0 would mean 2^0 or 1, which is the current behavior. More restrictive alignment requirements could be encoded easily. No ABI or API change needed. #define RF_ALIGNMENT_MASK 0xfc00 #define RF_ALIGNMENT_SHIFT 10 #define RF_ALIGNMENT_LOG2(x) (x << RF_ALIGNMENT_SHIFT) Warner To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
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