[OpenBIOS] [PATCH 4/6] escc.c: add empty slot-names property to serial ports

Programmingkid programmingkidx at gmail.com
Sat Feb 20 17:17:53 CET 2016

On Feb 20, 2016, at 10:51 AM, Mark Cave-Ayland wrote:

> This is required to enable the ports to be detected by OS X.
> Signed-off-by: Mark Cave-Ayland <mark.cave-ayland at ilande.co.uk>
> ---
> openbios-devel/drivers/escc.c |    2 ++
> 1 file changed, 2 insertions(+)
> diff --git a/openbios-devel/drivers/escc.c b/openbios-devel/drivers/escc.c
> index f194957..bb7b34c 100644
> --- a/openbios-devel/drivers/escc.c
> +++ b/openbios-devel/drivers/escc.c
> @@ -466,6 +466,8 @@ escc_add_channel(const char *path, const char *node, phys_addr_t addr,
>     NEWWORLD(set_property(dnode, "interrupts",
>              (char *)&props, 3 * sizeof(cell)));
> +    set_int_property(dnode, "slot-names", 0);
> +
>     device_end();
>     uart_init_line((unsigned char*)addr + offset + reg_offsets[legacy][index][0],
> -- 

Sorry but this logical change to the slot-names property does not make Mac OS X happy. The driver will just assume there is more than just a 32-bit number set to this property. 

This is the source code for the driver Mac OS X uses to read the slot-names property. 

tmpName = (char *) s->getBytesNoCopy() + sizeof(UInt32);
The s->getBytesNoCopy() code here is what is used to get the address of the start of the slot-names property's value. The " + sizeof(UInt32); " code is used to just skip over the beginning integer part of the property so that the driver can read the string part. In a perfect world the driver for Mac OS 9 and X would just see the zero and not bother trying to use the serial port. But unfortunately we don't have drivers that do something so logical. I did submit a patch that sets this property to this:

This is the value on real hardware. It also allows the Mac OS X driver to continue past where it would usually fail. The next thing to fix I would guess is adding dma support to the escc.c file. 

More information about the OpenBIOS mailing list