Date: Sun, 10 Feb 2019 01:13:32 -0800 From: Jason Harmening <jason.harmening@gmail.com> To: FreeBSD Arch <freebsd-arch@freebsd.org> Subject: Any desire for a more flexible bus_dmamem_alloc variant ? Message-ID: <ee0a8333-e5e8-0b4e-e5bd-7b1ad5410847@gmail.com>
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Hi everyone, It's really bugged me for years that bus_dmamem_alloc() just uses the tag's maximum size instead of allowing a size to be passed in. I got reminded of this again recently when looking over some busdma code. I know others have voiced this complaint in the past: https://lists.freebsd.org/pipermail/freebsd-current/2012-July/035281.html I used to work on an out-of-tree driver that could've benefited from something like this. It also seems like the benefits of using bus_dmamem_alloc() to always do the optimal thing instead of, say, rolling your own using kmem_alloc_[attr|contig] will increase as we adopt support for IOMMUs. I'd like to see if there's any interest in adding a bus_dmamem_alloc_attr() KPI that takes both a size and vm_memattr_t. Are there any potential in-tree consumers of such a thing? --Jason
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