Re: [Qemu-devel] [PATCH 1/2] debugexit: support for custom exit port (e.g LGPL'ed VGA BIOS port 0x501)

[Anthony Liguori <aliguori@us.ibm.com>]

Andreas Färber <afaerber@suse.de> writes:

> Am 06.07.2012 23:53, schrieb Hervé Poussineau:
>> Add generic support for simple I/O port which, when written to, cause
>> QEMU to exit with the given written value.
>> 
>> There is no vmstate associated with the debugging port, simply because
>> the entire interface is a single, stateless, write-only port.
>> 
>> Signed-off-by: Hervé Poussineau <hpoussin@reactos.org>
>> ---
>>  hw/debugexit.c        |   68 +++++++++++++++++++++++++++++++++++++++++++++++++
>>  hw/i386/Makefile.objs |    2 +-
>>  2 files changed, 69 insertions(+), 1 deletion(-)
>>  create mode 100644 hw/debugexit.c
>> 
>> diff --git a/hw/debugexit.c b/hw/debugexit.c
>> new file mode 100644
>> index 0000000..72ddf31
>> --- /dev/null
>> +++ b/hw/debugexit.c
>> @@ -0,0 +1,68 @@
>> +/*
>> + * QEMU debug exit port ("LGPL'ed-VGA-BIOS-style port 501/502") emulation
>> + *
>> + * Copyright (c) 2012 Herve Poussineau
>> + *
>> + * This program is free software; you can redistribute it and/or modify it
>> + * under the terms of the GNU General Public License as published by the
>> + * Free Software Foundation; either version 2 of the License, or (at your
>> + * option) any later version.
>> + *
>> + * This program is distributed in the hope that it will be useful,
>> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
>> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
>> + * See the GNU General Public License for more details.
>> + *
>> + * You should have received a copy of the GNU General Public License along
>> + * with this program; if not, see <http://www.gnu.org/licenses/>.
>> + */
>> +
>> +#include "isa.h"
>> +
>> +typedef struct ISADebugExitState {
>> +    ISADevice dev;
>> +    uint32_t iobase;
>> +    uint8_t access_size;
>> +} ISADebugExitState;
>> +
>> +static void debugexit_ioport_write(void *opaque, uint32_t addr, uint32_t val)
>> +{
>> +    exit((val << 1) | 1);
>
> I understand you're just moving code from patch 2/2 here, but in another
> thread it was stated that exit()ing from such writes can do bad things
> to the block layer (cleanups not happening) and should be replaced by
> qemu_request_shutdown() or something like that...

Not really.  This is the right behavior for this port.

Regards,

Anthony Liguori

>
> Andreas
>
>> +}
>> +
>> +static int debugexit_isa_initfn(ISADevice *dev)
>> +{
>> +    ISADebugExitState *isa = DO_UPCAST(ISADebugExitState, dev, dev);
>> +
>> +    register_ioport_write(isa->iobase, 1, isa->access_size,
>> +                          debugexit_ioport_write, NULL);
>> +    return 0;
>> +}
>> +
>> +static Property debugexit_isa_properties[] = {
>> +    DEFINE_PROP_HEX32("iobase", ISADebugExitState, iobase, 0x501),
>> +    DEFINE_PROP_UINT8("access-size", ISADebugExitState, access_size, 1),
>> +    DEFINE_PROP_END_OF_LIST(),
>> +};
>> +
>> +static void debugexit_isa_class_initfn(ObjectClass *klass, void *data)
>> +{
>> +    DeviceClass *dc = DEVICE_CLASS(klass);
>> +    ISADeviceClass *ic = ISA_DEVICE_CLASS(klass);
>> +    ic->init = debugexit_isa_initfn;
>> +    dc->props = debugexit_isa_properties;
>> +}
>> +
>> +static TypeInfo debugexit_isa_info = {
>> +    .name          = "isa-debugexit",
>> +    .parent        = TYPE_ISA_DEVICE,
>> +    .instance_size = sizeof(ISADebugExitState),
>> +    .class_init    = debugexit_isa_class_initfn,
>> +};
>> +
>> +static void debugexit_register_types(void)
>> +{
>> +    type_register_static(&debugexit_isa_info);
>> +}
>> +
>> +type_init(debugexit_register_types)
>> diff --git a/hw/i386/Makefile.objs b/hw/i386/Makefile.objs
>> index eb171b7..23be2d3 100644
>> --- a/hw/i386/Makefile.objs
>> +++ b/hw/i386/Makefile.objs
>> @@ -3,7 +3,7 @@ obj-y += apic_common.o apic.o kvmvapic.o
>>  obj-y += sga.o ioapic_common.o ioapic.o piix_pci.o
>>  obj-y += vmport.o
>>  obj-y += pci-hotplug.o smbios.o wdt_ib700.o
>> -obj-y += debugcon.o multiboot.o
>> +obj-y += debugcon.o debugexit.o multiboot.o
>>  obj-y += pc_piix.o
>>  obj-y += pc_sysfw.o
>>  obj-$(CONFIG_XEN) += xen_platform.o xen_apic.o
>> 
>
>
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