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-------- Forwarded Message --------
Subject: ACPICA missing support for device I/O port ranges
Date: Sat, 18 Nov 2017 18:52:54 +0100
From: Harald Böhm <>
To: '' <>

Hi all,

I've been working on a device driver lately and was having trouble
allocating its resources using bus_alloc_resource_any(), although its
I/O ports can be read from its _CRS.

This is the output of acpidump -td:

Device (GMUX)
    Name (_CRS, ResourceTemplate ()  // _CRS: Current Resource Settings
        IO (Decode16,
            0x0700,             // Range Minimum
            0x07FF,             // Range Maximum
            0x01,               // Alignment
            0xFF,               // Length

After digging into the code in /sys/dev/acpica/acpi_resources.c I was
able to find the problem. The function acpi_res_set_iorange(), which
seems to be responsible for calling bus_set_resource() is just a
function stub that prints a message that I/O ranges are not supported.

static void
acpi_res_set_iorange(device_t dev, void *context, uint64_t low,
                     uint64_t high, uint64_t length, uint64_t align)
    struct acpi_res_context     *cp = (struct acpi_res_context *)context;

    if (cp == NULL)
    device_printf(dev, "I/O range not supported\n");

After adding a call to bus_set_resource() to that function, I was able
to allocate the device's resources.

Does anyone know, why the function has not been implemented or why I/O
ranges are not supported?



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