On Sat, Oct 08, 2016 at 08:52:03AM +0200, Oliver Mangold wrote: > <https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/tree/arch?id=refs/tags/v4.8>Hi > everyone, > > I would like to report a what looks to me like a bug in the serial8250 > driver. The problem is, that the enumeration of legacy (ISA) serial devices > seems to be inconsistent between this driver and what the Grub2 bootloader > does. It seems in Linux the order of the serial ports is hardcoded here: > > --- linux/drivers/tty/serial/8250/8250_core.c --- > > static const struct old_serial_port old_serial_port[] = { > SERIAL_PORT_DFNS /* defined in asm/serial.h */ > }; > > --- > > It uses the traditional ordering 3F8,2F8,3E8,2E8: > > --- linux/arch/x86/include/asm/serial.h --- > > |#define SERIAL_PORT_DFNS \ /* UART CLK PORT IRQ FLAGS */\ { .uart = 0, > BASE_BAUD, 0x3F8, 4, STD_COMX_FLAGS }, /* ttyS0 */\ { .uart = 0, BASE_BAUD, > 0x2F8, 3, STD_COMX_FLAGS }, /* ttyS1 */\ { .uart = 0, BASE_BAUD, 0x3E8, 4, > STD_COMX_FLAGS }, /* ttyS2 */\ { .uart = 0, BASE_BAUD, 0x2E8, 3, > STD_COM4_FLAGS }, /* ttyS3 */| > > > --- > > Grub on the other hand looks up the order of the devices in the BIOS memory > area: > > --- grub-2.02/grub-core/term/ns8250.c --- > #ifdef GRUB_MACHINE_PCBIOS > #include <grub/machine/memory.h> > static const unsigned short *serial_hw_io_addr = (const unsigned short *) > GRUB_MEMORY_MACHINE_BIOS_DATA_AREA_ADDR; > #define GRUB_SERIAL_PORT_NUM 4 > --- > > This area is hardcoded at address 0x400: > > --- grub-2.02/include/grub/i386/pc/memory.h --- > #define GRUB_MEMORY_MACHINE_BIOS_DATA_AREA_ADDR 0x400 > --- > > I would like to note that this inconsistency is a real problem, as some > motherboards (like e.g. a Supermicro X10DRi with default BIOS settings) have > a different order stored there: > > --- > # hexdump -s 0x400 -n 8 /dev/mem > 0000400 02f8 03f8 0000 0000 > --- > > For later reference, the above code snippets are from Linux tag v4.8 and > Grub2 tag grub-2.02-beta3. As this sequence hasn't changed in the Linux kernel at all, isn't this a Grub issue? thanks, greg k-h -- To unsubscribe from this list: send the line "unsubscribe linux-serial" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
