[Bug 211484] Zynq/Zybo cannot mount USB drives as root

[bugzilla-noreply at freebsd.org]

https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=211484

            Bug ID: 211484
           Summary: Zynq/Zybo cannot mount USB drives as root
           Product: Base System
           Version: CURRENT
          Hardware: arm
                OS: Any
            Status: New
          Severity: Affects Only Me
          Priority: ---
         Component: arm
          Assignee: freebsd-arm at FreeBSD.org
          Reporter: thoma555-bsd at yahoo.com

Created attachment 173141
  --> https://bugs.freebsd.org/bugzilla/attachment.cgi?id=173141&action=edit
patch to zynq-7000.dtsi

A Zynq/Zybo system cannot mount a USB drive/stick as the root filesystem.  The
problem is the the ehci driver tries to DMA to a location in the first half
megabyte of memory space which has several caveats on Zynq including a hole
between 256K-512K that is inaccessible by bus masters.

Originally, I tried to avoid something like this happening by starting memory
at 0x100000 in the Zynq DTS file.  But, ubldr "fixes up" memory ranges using
information from u-boot (retrieved by a sysinfo call to the API).  That causes
the kernel to allocate the first megabyte.

The simplest work-around seems to be to add a “memreserve” property to the DTS.
 Also, It turns out that only the first half megabyte needs to be excluded.

-- 
You are receiving this mail because:
You are the assignee for the bug.