Date: Sun, 27 Jan 2008 18:02:13 +0100 From: Hans Petter Selasky <hselasky@c2i.net> To: current@freebsd.org Subject: BUS-DMA alignment check - false positives Message-ID: <200801271802.14312.hselasky@c2i.net>
next in thread | raw e-mail | index | archive | help
Hi,
When allocating DMA'able memory sometimes the virtual address can end up
non-aligned, while the physical address is correctly aligned. The question is
whether it is correct to mask the virtual address and not the physical
address:
i386/i386/busdma_machdep.c
} else if ((uintptr_t)*vaddr & (dmat->alignment - 1)) {
printf("bus_dmamem_alloc failed to align memory properly.\n");
}
When allocating 1<<15 bytes aligned at 1<<15 bytes.
bus_dmamem_alloc failed to align memory properly.
Physaddr=0x3e030000 rem=0x00000000
--HPS
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?200801271802.14312.hselasky>