[Qemu-devel] [Bug 897771] Re: qemu 1.0-rc4 no longer able to boot NetBSD-current/i386

[Andreas Gustafsson]

I found the cause of the regression.  As as Stefan Weil already figured,
it was caused by the following commit:

    commit d0ed8076cbdc26138a7e33fed5e45a35d019a103
    Author: Avi Kivity <address@hidden>
    Date: Sun Jul 24 17:47:18 2011 +0300

        pci_host: convert conf index and data ports to memory API

        Reviewed-by: Richard Henderson <address@hidden>
        Signed-off-by: Avi Kivity <address@hidden>

This commit incorrectly changed the emulation of the PCI configuration
register at I/O port 0xCF8.  Before the commit, an outb to port 0xCFB
or an outw to port 0xCFA had no effect, but after the commit, they
change the value of the CONFIG_ADDRESS DWORD register at 0xCF8.  This
is contrary to the behavior of real PC hardware, and contrary to the
PCI standard which clearly states that the only I/O space consumed by
the CONFIG_ADDRESS register is the DWORD at address 0xCF8.

Changing pci_host_config_write() to ignore writes with addr != 0 is
sufficient for qemu to again be able to boot NetBSD.  For full
compliance with the PCI standard, it should also ignore writes with
size != 4, and a similar change should probably also be made to
pci_host_config_read().

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https://bugs.launchpad.net/bugs/897771

Title:
  qemu 1.0-rc4 no longer able to boot NetBSD-current/i386

Status in QEMU:
  Confirmed

Bug description:
  Booting a NetBSD-current/i386 install CD using qemu 1.0-rc4 fails. The
  same CD does boot in earlier versions of qemu, for example, 0.11.0.

  To reproduce, download the

    http://www.gson.org/netbsd/bugs/qemu/boot-com-201111270050Z.iso

  and attempt to boot it with:

    qemu -nographic -cdrom boot-com-201111270050Z.iso

  This fails with a guest kernel panic:

    NetBSD 5.99.57 (GENERIC) #0: Sun Nov 27 07:41:56 UTC 2011
            
address@hidden:/home/builds/ab/HEAD/i386/201111270050Z-obj/home/builds/ab/HEAD/src/sys/arch/i386/compile/GENERIC
    total memory = 127 MB
    avail memory = 112 MB
    cprng kernel: WARNING insufficient entropy at creation.
    mainbus0 (root)
    cpu0 at mainbus0 apid 0: QEMU Virtual CPU version 0.15.93, id 0x633
    ioapic0 at mainbus0 apid 1
    acpi0 at mainbus0: Intel ACPICA 20110623
    panic: pci_make_tag: bad request
    fatal breakpoint trap in supervisor mode
    trap type 1 code 0 eip c0269b04 cs 8 eflags 282 cr2 0 ilevel 8
    Stopped in pid 0.1 (system) at  netbsd:breakpoint+0x4:  popl    %ebp
    db{0}>  t
    
breakpoint(c0c04c75,c0cc2f80,c0bc91a4,c0e358e4,2,c11b70d6,c0e35908,c053999d,c0cdef20,0)
 at netbsd:breakpoint+0x4
    
vpanic(c0bc91a4,c0e358e4,c117d068,f,c11e6fcc,0,c0e35918,c0665969,c0bc91a4,c0b1bf4c)
 at netbsd:vpanic+0x1e2
    printf_nolog(c0bc91a4,c0b1bf4c,c0e35908,c010d957,8,c0c1f2c0,0,0,c0d08e20,0) 
at netbsd:printf_nolog
    pci_decompose_tag(c0e3599c,0,0,10,0,ca675898,c0e35988,c0d08e20,c11b9200,0) 
at netbsd:pci_decompose_tag
    acpi_pci_link_add_reference(c12011c0,0,0,10,0,ca41eb90,0,3,0,4) at 
netbsd:acpi_pci_link_add_reference+0xb2
    
mpacpi_find_interrupts(ca41eb90,c0116a4a,c0116a5e,0,ca41eb90,c0e35b50,c0e35aa8,c01180c7,c,c0116a4a)
 at netbsd:mpacpi_find_interrupts+0x5ea
    
acpi_md_callback(c,c0116a4a,c0116a5e,0,1,ca3fd7cc,1,c078e2e4,c0cb6ce0,ca435ea0) 
at netbsd:acpi_md_callback+0x1c
    
acpi_attach(ca660500,ca660d00,c0e35b50,0,c0e35b50,80,f,10,c0b5dcd9,c0e35b42) at 
netbsd:acpi_attach+0x14a
    
config_attach_loc(ca660500,c0c1d7a0,0,c0e35b50,0,0,2589,58421301,4350,53445842) 
at netbsd:config_attach_loc+0x176
    
config_found_ia(ca660500,c0b59f3c,c0e35b50,0,4f424101,20534843,80,f,c0c2bbe0,c0c2bc00)
 at netbsd:config_found_ia+0x36
    
mainbus_rescan(ca660500,c0b59f3c,0,ca660500,c0cb6ce0,c0bd71ce,c0e35bd8,c093575c,ca437f28,c0b8e0a1)
 at netbsd:mainbus_rescan+0x1c2
    
mainbus_attach(0,ca660500,0,c078f4b7,c0b59187,c0b59187,636f4200,7368,3001403,101)
 at netbsd:mainbus_attach+0xb4
    config_attach_loc(0,c0c1bbb0,0,0,0,7368,f10,0,c0b59187,e3b000) at 
netbsd:config_attach_loc+0x176
    config_attach(0,c0c1bbb0,0,0,1984,c0cc5680,c0e35cd8,c01f224e,c0b59187,0) at 
netbsd:config_attach+0x2e
    config_rootfound(c0b59187,0,0,8,1984,1984,c0e35d40,c04b78d8,c0ba59a1,6) at 
netbsd:config_rootfound+0x42
    cpu_configure(c0ba59a1,6,3,0,ffff,f9b00,ffff,f9300,0,0) at 
netbsd:cpu_configure+0x2a
    main(0,0,0,0,0,0,0,0,0,0) at netbsd:main+0x2ba
    db{0}>

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