sdcard: Allow sdcard addresses to be specified in CBFS files

Allow a hardcoded address to be specified in cbfs files with a prefix
of "etc/sdcard".  Some real-world devices have valid SDHCI controllers
that do not show up as PCI devices.

Signed-off-by: Kevin O'Connor <kevin@koconnor.net>

1 files changed, 1 insertions, 0 deletions

diff --git a/docs/Runtime_config.md b/docs/Runtime_config.md
index 4ac0eae..d6fea28 100644
--- a/docs/Runtime_config.md
+++ b/docs/Runtime_config.md
@@ -188,3 +188,4 @@ There are several additional configuration options available in the
 | floppy0             | Set this to the type of the first floppy drive in the system (only type 4 for 3.5 inch drives is supported).
 | floppy1             | The type of the second floppy drive in the system. See the description of **floppy0** for more info.
 | threads             | By default, SeaBIOS will parallelize hardware initialization during bootup to reduce boot time. Multiple hardware devices can be initialized in parallel between vga initialization and option rom initialization. One can set this file to a value of zero to force hardware initialization to run serially. Alternatively, one can set this file to 2 to enable early hardware initialization that runs in parallel with vga, option rom initialization, and the boot menu.
+| sdcard*             | One may create one or more files with an "sdcard" prefix (eg, "etc/sdcard0") with the physical memory address of an SDHCI controller (one memory address per file).  This may be useful for SDHCI controllers that do not appear as PCI devices, but are mapped to a consistent memory address.