I've had a look at your am53c974 boot floppy with PcSCSI drivers and I'm fairly sure that disabling INT13 support isn't helping here. With your custom SeaBIOS I see a hang issuing the first SCSI command: without your custom SeaBIOS I can see that the default SeaBIOS issues several successful commands to the SCSI bus before booting from the floppy.
Dropping the -bios option and booting your floppy here I see the following sequence with -trace 'scsi*' -trace 'esp*' after the BIOS has initialised: esp_mem_writeb reg[3]: 0x42 -> 0x02 esp_mem_writeb_cmd_reset Chip reset (0x02) esp_mem_writeb reg[3]: 0x02 -> 0x80 esp_mem_writeb_cmd_nop NOP (0x80) esp_mem_writeb reg[11]: 0x00 -> 0x40 esp_mem_readb reg[14]: 0x12 esp_pci_sbac_read sbac: 0x00000000 esp_pci_sbac_write sbac: 0x00000000 -> 0x02000000 esp_mem_writeb reg[3]: 0x80 -> 0x02 esp_mem_writeb_cmd_reset Chip reset (0x02) esp_mem_writeb reg[3]: 0x02 -> 0x80 esp_mem_writeb_cmd_nop NOP (0x80) esp_mem_writeb reg[8]: 0x00 -> 0x17 esp_mem_writeb reg[12]: 0x00 -> 0x88 esp_mem_writeb reg[13]: 0x00 -> 0x40 esp_mem_writeb reg[11]: 0x00 -> 0x40 esp_mem_writeb reg[9]: 0x00 -> 0x07 esp_mem_writeb reg[5]: 0x00 -> 0x8d esp_mem_writeb reg[5]: 0x8d -> 0x02 esp_mem_readb reg[8]: 0x17 esp_mem_writeb reg[8]: 0x17 -> 0x07 esp_mem_writeb reg[4]: 0x00 -> 0x00 esp_mem_writeb reg[3]: 0x80 -> 0x01 esp_mem_writeb_cmd_flush Flush FIFO (0x01) esp_mem_writeb reg[2]: 0x00 -> 0x00 esp_mem_writeb reg[2]: 0x00 -> 0x00 esp_mem_writeb reg[2]: 0x00 -> 0x00 esp_mem_writeb reg[2]: 0x00 -> 0x00 esp_mem_writeb reg[2]: 0x00 -> 0x00 esp_mem_writeb reg[2]: 0x00 -> 0x00 esp_mem_writeb reg[3]: 0x01 -> 0x41 esp_mem_writeb_cmd_sel Select without ATN (0x41) esp_get_cmd len 6 target 0 esp_do_busid_cmd busid 0x0 scsi_req_parsed target 0 lun 0 tag 0 command 0 dir 0 length 0 scsi_req_parsed_lba target 0 lun 0 tag 0 command 0 lba 0 scsi_req_alloc target 0 lun 0 tag 0 scsi_disk_new_request Command: lun=0 tag=0x0 data= 0x00 0x00 0x00 0x00 0x00 0x00 scsi_test_unit_ready target 0 lun 0 tag 0 scsi_req_dequeue target 0 lun 0 tag 0 esp_command_complete SCSI Command complete esp_raise_irq Raise IRQ esp_lower_drq Lower DREQ ****** esp_pci_dma_read reg[5]: 0x00000018 esp_mem_readb reg[4]: 0x93 esp_mem_readb reg[6]: 0x00 esp_lower_irq Lower IRQ esp_mem_readb reg[5]: 0x18 esp_mem_readb reg[8]: 0x07 esp_mem_writeb reg[8]: 0x07 -> 0x47 esp_mem_writeb reg[3]: 0x41 -> 0x03 esp_mem_writeb_cmd_bus_reset Bus reset (0x03) ****** The loading of the "test unit ready" command and execution look fine to me: QEMU's SCSI layer is executing the command (indicating success) and raises the ESP IRQ. However at this point in the section marked by "******" the ASPI driver seems not be happy with the RSTAT/RINTR register contents or the 0x18 read back from the PCI DMA registers, issues a bus reset and stops. What is interesting here is that the "Select without ATN (0x41)" command issued is a non-DMA command so I wouldn't expect it to affect the ESP PCI DMA register state, but I suspect you'll need to have a look what the driver is doing using a disassembler/gdbstub and the am53c974 datasheet to try and understand what is happening here. Finally it may be worth checking the IRQ routing with -trace 'pci*' to see if SeaBIOS updates the PCI "Interrupt Pin" register indicating where it thinks the IRQ should be routed, and stepping through the esp_raise_irq() in QEMU for the final test unit ready command to ensure that all of QEMU, SeaBIOS and AMSIDA.SYS all agree on what IRQ is being used. -- You received this bug notification because you are a member of qemu- devel-ml, which is subscribed to QEMU. https://bugs.launchpad.net/bugs/1921635 Title: ESP SCSI adapter not working with DOS ASPI drivers Status in QEMU: New Bug description: I have been trying to install the DOS ASPI drivers for the ESP scsi card. Both in am53c974 and dc390 modes. Neither works but they don't work in different ways. The following things appear to be problematic: * The am53c974 should work with the PcSCSI drivers (AMSIDA.SYS) but the ASPI driver never manages to get past initializing the card. The VM never continues. * The dc390 ASPI driver fares a little better. The ASPI driver loads and is semi-functional but the drivers for the peripherals don't work. - ASPI.SYS (creative name) loads - TRMDISK.SYS fails to load when a cd-drive is attached and will crashs scanning the scsi-id where the cd drive is attached - TRMDISK.SYS loads without a CD drive attached but fails to read any scsi-hd devices attached. The TFDISK.EXE formatter crashes. - TRMCD.SYS loads, but can not detect any CD drives. The various permutations: am53c974 hang on ASPI driver load: (CD only attached) ~/src/qemu/build/qemu-system-i386 -m 64 -device am53c974,id=scsi0 -device scsi-cd,drive=drive0,bus=scsi0.0,channel=0,scsi-id=0,lun=0 -drive file=../Windows\ 98\ Second\ Edition.iso,if=none,id=drive0 -vga cirrus -fda am53c974_aspi.img -bios /home/hp/src/seabios/out/bios.bin -boot a -trace 'scsi*' -trace 'esp*' -D log dc390 crash because of CDROM attachment and loading TRMDISK.SYS (Only CD attached) ~/src/qemu/build/qemu-system-i386 -m 64 -device dc390,id=scsi0,rombar=0 -device scsi-cd,drive=drive0,bus=scsi0.0,channel=0,scsi-id=0,lun=0 -drive file=../Windows\ 98\ Second\ Edition.iso,if=none,id=drive0 -vga cirrus -fda dc390_all.img -bios /home/hp/src/seabios/out/bios.bin -boot a -trace 'scsi*' -trace 'esp*' -D log dc390 successful boot, but TRMDISK.SYS not working (TFDISK.EXE will crash) ~/src/qemu/build/qemu-system-i386 -m 64 -device dc390,id=scsi0 -device scsi-hd,drive=drive0,bus=scsi0.0,channel=0,scsi-id=0,lun=0,logical_block_size=512 -drive file=small.qcow2,if=none,id=drive0 -vga cirrus -fda dc390_all.img -bios /home/hp/src/seabios/out/bios.bin -boot a -trace 'scsi*' -trace 'esp*' -D log dc390 successful boot, TRMDISK.SYS not loaded, only TRMCD.SYS. CDROM not detected ~/src/qemu/build/qemu-system-i386 -m 64 -device dc390,id=scsi0,rombar=0 -device scsi-cd,drive=drive0,bus=scsi0.0,channel=0,scsi-id=0,lun=0 -drive file=../Windows\ 98\ Second\ Edition.iso,if=none,id=drive0 -vga cirrus -fda dc390_cd.img -bios /home/hp/src/seabios/out/bios.bin -boot a -trace 'scsi*' -trace 'esp*' -D log All of these tests were done on 7b9a3c9f94bcac23c534bc9f42a9e914b433b299 as well as the 'esp-next' branch found here: https://github.com/mcayland/qemu/tree/esp-next The bios file is a seabios master with all int13 support disabled. With it enabled even less works but I figured this would be a seabios bug and not a qemu one. The actual iso and qcow2 files used don't appear the matter. the 'small.qcow2' is an empty drive of 100MB. I have also tried other ISOs in the CD drives, or even not put any cd in the drives with the same results. I will attach all of the above images. 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