Date: Thu, 29 Mar 2012 15:33:44 +0000 (UTC) From: Hans Petter Selasky <hselasky@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r233662 - head/sys/dev/pci Message-ID: <201203291533.q2TFXisu099144@svn.freebsd.org>
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Author: hselasky Date: Thu Mar 29 15:33:44 2012 New Revision: 233662 URL: http://svn.freebsd.org/changeset/base/233662 Log: Fix for boot issue: Don't disable BARs on AGP devices. In general: Don't disable BARs on any PCI display devices, because doing that can sometimes cause the main memory bus to stop working, causing all memory reads to return nothing but 0xFFFFFFFF, even though the memory location was previously written. After a while a privileged instruction fault will appear and then nothing more can be debugged. The reason for this behaviour is unknown. MFC after: 1 week Modified: head/sys/dev/pci/pci.c Modified: head/sys/dev/pci/pci.c ============================================================================== --- head/sys/dev/pci/pci.c Thu Mar 29 14:53:14 2012 (r233661) +++ head/sys/dev/pci/pci.c Thu Mar 29 15:33:44 2012 (r233662) @@ -2590,6 +2590,27 @@ pci_write_bar(device_t dev, struct pci_m struct pci_devinfo *dinfo; int ln2range; + /* + * Don't disable BARs on AGP devices. In general: Don't + * disable BARs on any PCI display devices, because doing that + * can sometimes cause the main memory bus to stop working, + * causing all memory reads to return nothing but 0xFFFFFFFF, + * even though the memory location was previously written. + * After a while a privileged instruction fault will appear + * and then nothing more can be debugged. + * The reason for this behaviour is unknown. + */ + if (base == 0 && pci_get_class(dev) == PCIC_DISPLAY) { + device_printf(device_get_parent(dev), + "pci%d:%d:%d:%d BARs on display devices " + "should not be disabled.\n", + pci_get_domain(dev), + pci_get_bus(dev), + pci_get_slot(dev), + pci_get_function(dev)); + return; + } + /* The device ROM BAR is always a 32-bit memory BAR. */ dinfo = device_get_ivars(dev); if (PCIR_IS_BIOS(&dinfo->cfg, pm->pm_reg))
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