Date: Sat, 6 Aug 2016 18:54:20 -0700 From: Adrian Chadd <adrian.chadd@gmail.com> To: Thomas Skibo <thomasskibo@yahoo.com> Cc: "freebsd-arm@freebsd.org" <freebsd-arm@freebsd.org> Subject: Re: Zynq/Zybo USB bug: ubldr "fixes" my device tree Message-ID: <CAJ-VmokhEeqyTpdhmZ7g-CPwe8M-0cHC9Q6ExAczAO1bS7CXrg@mail.gmail.com> In-Reply-To: <7C4D45AC-3DDB-46FE-85AB-5F692E5C1283@yahoo.com> References: <7C4D45AC-3DDB-46FE-85AB-5F692E5C1283@yahoo.com>
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hi! Cool! can you create a PR for that? -adrian On 31 July 2016 at 10:55, Thomas Skibo via freebsd-arm <freebsd-arm@freebsd.org> wrote: > > Hello. > > I finally tracked down a bug that kept me from being able to use a USB dr= ive as root on a Zybo (or Zedboard). Mounting USB drives has worked fine b= efore but using one as root would fail. > > The first megabyte of memory space on Zynq has several caveats including = a hole between 256K-512K that is inaccessible by bus masters. My solution = was to simply ignore the first megabyte by starting memory at 0x100000 in m= y DTS file(s). But, I discovered that the first megabyte was being allocat= ed and the ehci device hung trying to DMA to the hole. It turns out that u= bldr, after loading the board.dtb file, proceeded to =E2=80=9Cfix up=E2=80= =9D the device tree from memory range information it got in a sysinfo call = to u-boot=E2=80=99s API. The memory range started at 0. > > The simplest work-around seems to be to add a =E2=80=9Cmemreserve=E2=80= =9D property to the DTS. Also, It turns out that only the first half megab= yte needs to be ignored. Patch attached. > > =E2=80=94 > Thomas Skibo > thomasskibo@yahoo.com > > > > _______________________________________________ > freebsd-arm@freebsd.org mailing list > https://lists.freebsd.org/mailman/listinfo/freebsd-arm > To unsubscribe, send any mail to "freebsd-arm-unsubscribe@freebsd.org"
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