Peter Maydell 0c285e0128 hw/block/fdc-sysbus: Always mark sysbus floppy controllers as not having DMA ... The sysbus floppy controllers (devices sysbus-fdc and sun-fdtwo) don't support DMA. The core floppy controller code expects this to be indicated by setting FDCtrl::dma_chann to -1. This used to be done in the device instance_init functions sysbus_fdc_initfn() and sun4m_fdc_initfn(), but in commit 1430759ec3 we refactored this code and accidentally lost the setting of dma_chann. For sysbus-fdc this has no ill effects because we were redundantly also setting dma_chann in fdctrl_init_sysbus(), but for sun-fdtwo this means that guests which try to enable DMA on the floppy controller will cause QEMU to crash because FDCtrl::dma is NULL. Set dma_chann to -1 in the common instance init, and remove the redundant code in fdctrl_init_sysbus() that is also setting it. There is a six-year-old FIXME comment in the jazz board code to the effect that in theory it should support doing DMA via a custom DMA controller. If anybody ever chooses to fix that they can do it by adding support for setting both FDCtrl::dma_chann and FDCtrl::dma. (A QOM link property 'dma-controller' on the sysbus device which can be set to an instance of IsaDmaClass is probably the way to go.) Fixes: 1430759ec3 ("hw/block/fdc: Extract SysBus floppy controllers to fdc-sysbus.c") Resolves: https://gitlab.com/qemu-project/qemu/-/issues/958 Signed-off-by: Peter Maydell <peter.maydell@linaro.org> Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org> Reviewed-by: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk> Message-Id: <20220505101842.2757905-1-peter.maydell@linaro.org> Signed-off-by: Philippe Mathieu-Daudé <f4bug@amsat.org>		2022-06-11 11:36:14 +02:00
..
block.h	block: Add backend_defaults property	2021-07-06 14:28:55 +01:00
fdc.h	hw/block/fdc-sysbus: Always mark sysbus floppy controllers as not having DMA	2022-06-11 11:36:14 +02:00
flash.h	vmstate: Constify some VMStateDescriptions	2021-05-02 17:24:50 +02:00
swim.h	Clean up includes	2020-12-10 17:16:44 +01:00