Date: Wed, 18 Nov 2015 22:20:13 +0000 (UTC) From: "Conrad E. Meyer" <cem@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r291030 - head/sys/dev/ntb/ntb_hw Message-ID: <201511182220.tAIMKD7o084202@repo.freebsd.org>
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Author: cem Date: Wed Nov 18 22:20:13 2015 New Revision: 291030 URL: https://svnweb.freebsd.org/changeset/base/291030 Log: ntb_hw: Add tunable to disable write-combining The tunable 'hw.ntb.enable_writecombine' may be set to zero to administratively disable write combining the mapped NTB region. Sponsored by: EMC / Isilon Storage Division Modified: head/sys/dev/ntb/ntb_hw/ntb_hw.c Modified: head/sys/dev/ntb/ntb_hw/ntb_hw.c ============================================================================== --- head/sys/dev/ntb/ntb_hw/ntb_hw.c Wed Nov 18 22:20:04 2015 (r291029) +++ head/sys/dev/ntb/ntb_hw/ntb_hw.c Wed Nov 18 22:20:13 2015 (r291030) @@ -326,6 +326,10 @@ SYSCTL_UINT(_hw_ntb, OID_AUTO, debug_lev } \ } while (0) +static unsigned g_ntb_enable_wc = 1; +SYSCTL_UINT(_hw_ntb, OID_AUTO, enable_writecombine, CTLFLAG_RDTUN, + &g_ntb_enable_wc, 0, "Set to 1 to map memory windows write combining"); + static struct ntb_hw_info pci_ids[] = { /* XXX: PS/SS IDs left out until they are supported. */ { 0x0C4E8086, "BWD Atom Processor S1200 Non-Transparent Bridge B2B", @@ -766,10 +770,13 @@ map_memory_window_bar(struct ntb_softc * save_bar_parameters(bar); } + print_map_success(ntb, bar, "mw"); + if (g_ntb_enable_wc == 0) + return (0); + /* Mark bar region as write combining to improve performance. */ rc = pmap_change_attr((vm_offset_t)bar->vbase, bar->size, VM_MEMATTR_WRITE_COMBINING); - print_map_success(ntb, bar, "mw"); if (rc == 0) device_printf(ntb->device, "Marked BAR%d v:[%p-%p] p:[%p-%p] as "
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