e3089a0318
The change makes the user and kernel address spaces on i386 independent, giving each almost the full 4G of usable virtual addresses except for one PDE at top used for trampoline and per-CPU trampoline stacks, and system structures that must be always mapped, namely IDT, GDT, common TSS and LDT, and process-private TSS and LDT if allocated. By using 1:1 mapping for the kernel text and data, it appeared possible to eliminate assembler part of the locore.S which bootstraps initial page table and KPTmap. The code is rewritten in C and moved into the pmap_cold(). The comment in vmparam.h explains the KVA layout. There is no PCID mechanism available in protected mode, so each kernel/user switch forth and back completely flushes the TLB, except for the trampoline PTD region. The TLB invalidations for userspace becomes trivial, because IPI handlers switch page tables. On the other hand, context switches no longer need to reload %cr3. copyout(9) was rewritten to use vm_fault_quick_hold(). An issue for new copyout(9) is compatibility with wiring user buffers around sysctl handlers. This explains two kind of locks for copyout ptes and accounting of the vslock() calls. The vm_fault_quick_hold() AKA slow path, is only tried after the 'fast path' failed, which temporary changes mapping to the userspace and copies the data to/from small per-cpu buffer in the trampoline. If a page fault occurs during the copy, it is short-circuit by exception.s to not even reach C code. The change was motivated by the need to implement the Meltdown mitigation, but instead of KPTI the full split is done. The i386 architecture already shows the sizing problems, in particular, it is impossible to link clang and lld with debugging. I expect that the issues due to the virtual address space limits would only exaggerate and the split gives more liveness to the platform. Tested by: pho Discussed with: bde Sponsored by: The FreeBSD Foundation MFC after: 1 month Differential revision: https://reviews.freebsd.org/D14633
273 lines
7.5 KiB
C
273 lines
7.5 KiB
C
/*-
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* SPDX-License-Identifier: BSD-4-Clause
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*
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* Copyright (C) 2003
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* Hidetoshi Shimokawa. All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. All advertising materials mentioning features or use of this software
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* must display the following acknowledgement:
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*
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* This product includes software developed by Hidetoshi Shimokawa.
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*
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* 4. Neither the name of the author nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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* $Id: dcons_crom.c,v 1.8 2003/10/23 15:47:21 simokawa Exp $
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* $FreeBSD$
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*/
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#include <sys/param.h>
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#include <sys/kernel.h>
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#include <sys/module.h>
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#include <sys/systm.h>
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#include <sys/types.h>
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#include <sys/conf.h>
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#include <sys/malloc.h>
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#include <sys/bus.h>
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#include <machine/bus.h>
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#include <dev/firewire/firewire.h>
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#include <dev/firewire/firewirereg.h>
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#include <dev/firewire/iec13213.h>
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#include <dev/dcons/dcons.h>
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#include <dev/dcons/dcons_os.h>
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#include <sys/cons.h>
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#if (defined(__i386__) || defined(__amd64__))
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#include <vm/vm.h>
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#include <vm/vm_param.h>
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#include <vm/pmap.h>
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#include <machine/segments.h> /* for idt */
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#endif
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static bus_addr_t dcons_paddr;
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static int force_console = 0;
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TUNABLE_INT("hw.firewire.dcons_crom.force_console", &force_console);
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#define ADDR_HI(x) (((x) >> 24) & 0xffffff)
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#define ADDR_LO(x) ((x) & 0xffffff)
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struct dcons_crom_softc {
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struct firewire_dev_comm fd;
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struct crom_chunk unit;
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struct crom_chunk spec;
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struct crom_chunk ver;
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bus_dma_tag_t dma_tag;
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bus_dmamap_t dma_map;
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bus_addr_t bus_addr;
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eventhandler_tag ehand;
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};
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static void
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dcons_crom_identify(driver_t *driver, device_t parent)
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{
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BUS_ADD_CHILD(parent, 0, "dcons_crom", device_get_unit(parent));
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}
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static int
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dcons_crom_probe(device_t dev)
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{
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device_t pa;
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pa = device_get_parent(dev);
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if(device_get_unit(dev) != device_get_unit(pa)){
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return(ENXIO);
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}
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device_set_desc(dev, "dcons configuration ROM");
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return (0);
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}
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#if (defined(__i386__) || defined(__amd64__))
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static void
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dcons_crom_expose_idt(struct dcons_crom_softc *sc)
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{
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static off_t idt_paddr;
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/* XXX */
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#ifdef __amd64__
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idt_paddr = (char *)idt - (char *)KERNBASE;
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#else /* __i386__ */
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idt_paddr = (off_t)pmap_kextract((vm_offset_t)idt);
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#endif
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crom_add_entry(&sc->unit, DCONS_CSR_KEY_RESET_HI, ADDR_HI(idt_paddr));
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crom_add_entry(&sc->unit, DCONS_CSR_KEY_RESET_LO, ADDR_LO(idt_paddr));
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}
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#endif
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static void
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dcons_crom_post_busreset(void *arg)
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{
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struct dcons_crom_softc *sc;
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struct crom_src *src;
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struct crom_chunk *root;
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sc = (struct dcons_crom_softc *) arg;
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src = sc->fd.fc->crom_src;
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root = sc->fd.fc->crom_root;
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bzero(&sc->unit, sizeof(struct crom_chunk));
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crom_add_chunk(src, root, &sc->unit, CROM_UDIR);
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crom_add_entry(&sc->unit, CSRKEY_SPEC, CSRVAL_VENDOR_PRIVATE);
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crom_add_simple_text(src, &sc->unit, &sc->spec, "FreeBSD");
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crom_add_entry(&sc->unit, CSRKEY_VER, DCONS_CSR_VAL_VER);
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crom_add_simple_text(src, &sc->unit, &sc->ver, "dcons");
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crom_add_entry(&sc->unit, DCONS_CSR_KEY_HI, ADDR_HI(dcons_paddr));
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crom_add_entry(&sc->unit, DCONS_CSR_KEY_LO, ADDR_LO(dcons_paddr));
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#if (defined(__i386__) || defined(__amd64__))
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dcons_crom_expose_idt(sc);
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#endif
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}
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static void
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dmamap_cb(void *arg, bus_dma_segment_t *segments, int seg, int error)
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{
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struct dcons_crom_softc *sc;
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if (error)
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printf("dcons_dmamap_cb: error=%d\n", error);
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sc = (struct dcons_crom_softc *)arg;
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sc->bus_addr = segments[0].ds_addr;
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bus_dmamap_sync(sc->dma_tag, sc->dma_map, BUS_DMASYNC_PREWRITE);
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device_printf(sc->fd.dev,
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"bus_addr 0x%jx\n", (uintmax_t)sc->bus_addr);
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if (dcons_paddr != 0) {
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/* XXX */
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device_printf(sc->fd.dev, "dcons_paddr is already set\n");
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return;
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}
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dcons_conf->dma_tag = sc->dma_tag;
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dcons_conf->dma_map = sc->dma_map;
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dcons_paddr = sc->bus_addr;
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/* Force to be the high-level console */
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if (force_console)
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cnselect(dcons_conf->cdev);
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}
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static void
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dcons_crom_poll(void *p, int arg)
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{
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struct dcons_crom_softc *sc = (struct dcons_crom_softc *) p;
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sc->fd.fc->poll(sc->fd.fc, -1, -1);
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}
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static int
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dcons_crom_attach(device_t dev)
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{
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struct dcons_crom_softc *sc;
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int error;
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if (dcons_conf->buf == NULL)
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return (ENXIO);
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sc = (struct dcons_crom_softc *) device_get_softc(dev);
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sc->fd.fc = device_get_ivars(dev);
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sc->fd.dev = dev;
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sc->fd.post_explore = NULL;
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sc->fd.post_busreset = (void *) dcons_crom_post_busreset;
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/* map dcons buffer */
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error = bus_dma_tag_create(
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/*parent*/ sc->fd.fc->dmat,
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/*alignment*/ sizeof(u_int32_t),
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/*boundary*/ 0,
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/*lowaddr*/ BUS_SPACE_MAXADDR,
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/*highaddr*/ BUS_SPACE_MAXADDR,
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/*filter*/NULL, /*filterarg*/NULL,
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/*maxsize*/ dcons_conf->size,
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/*nsegments*/ 1,
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/*maxsegsz*/ BUS_SPACE_MAXSIZE_32BIT,
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/*flags*/ BUS_DMA_ALLOCNOW,
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/*lockfunc*/busdma_lock_mutex,
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/*lockarg*/&Giant,
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&sc->dma_tag);
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if (error != 0)
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return (error);
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error = bus_dmamap_create(sc->dma_tag, BUS_DMA_COHERENT, &sc->dma_map);
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if (error != 0)
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return (error);
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error = bus_dmamap_load(sc->dma_tag, sc->dma_map,
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(void *)dcons_conf->buf, dcons_conf->size,
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dmamap_cb, sc, 0);
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if (error != 0)
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return (error);
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sc->ehand = EVENTHANDLER_REGISTER(dcons_poll, dcons_crom_poll,
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(void *)sc, 0);
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return (0);
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}
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static int
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dcons_crom_detach(device_t dev)
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{
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struct dcons_crom_softc *sc;
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sc = (struct dcons_crom_softc *) device_get_softc(dev);
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sc->fd.post_busreset = NULL;
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if (sc->ehand)
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EVENTHANDLER_DEREGISTER(dcons_poll, sc->ehand);
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/* XXX */
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if (dcons_conf->dma_tag == sc->dma_tag)
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dcons_conf->dma_tag = NULL;
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bus_dmamap_unload(sc->dma_tag, sc->dma_map);
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bus_dmamap_destroy(sc->dma_tag, sc->dma_map);
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bus_dma_tag_destroy(sc->dma_tag);
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return 0;
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}
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static devclass_t dcons_crom_devclass;
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static device_method_t dcons_crom_methods[] = {
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/* device interface */
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DEVMETHOD(device_identify, dcons_crom_identify),
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DEVMETHOD(device_probe, dcons_crom_probe),
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DEVMETHOD(device_attach, dcons_crom_attach),
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DEVMETHOD(device_detach, dcons_crom_detach),
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{ 0, 0 }
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};
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static driver_t dcons_crom_driver = {
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"dcons_crom",
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dcons_crom_methods,
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sizeof(struct dcons_crom_softc),
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};
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DRIVER_MODULE(dcons_crom, firewire, dcons_crom_driver,
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dcons_crom_devclass, 0, 0);
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MODULE_VERSION(dcons_crom, 1);
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MODULE_DEPEND(dcons_crom, dcons,
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DCONS_VERSION, DCONS_VERSION, DCONS_VERSION);
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MODULE_DEPEND(dcons_crom, firewire, 1, 1, 1);
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