Re: [U-Boot] [PATCH 1/1] board: arm: Add support for Broadcom BCM7445D0

6 Jun 2018

      Florian Fainelli f.fainelli@gmail.com writes:
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On 05/10/2018 06:04 AM, Thomas Fitzsimmons wrote:
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Florian Fainelli f.fainelli@gmail.com writes:
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On 05/06/2018 04:09 AM, Thomas Fitzsimmons wrote:
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+config BCMSTB_ACCOMMODATE_STBLINUX

bool ""
default y
help
 This prevents U-Boot from adding memory reservations for the

     lengths of initramfs and DTB.  Without skipping these,

     stblinux's "contiguous memory allocator" (CMA) Linux driver

     (cma_driver) will allocate memory ranges smaller than what

     are actually available, because it only checks reservation

     sizes.  It doesn't check if the reserved range overlaps the

     range it allocates.  stblinux also tries to move the DTB to

     a lower memory location early in the Linux boot.  If the FIT

     image specifies a load address for the initramfs then

     sometimes the DTB is moved into the range where the

     initramfs image is loaded.  Defining this will mean that

     FIT-provided initramfs load addresses are ignored.

What STB Linux kernel did you observe this with? I am afraid this is
still true about the ranges vs. allocation even in newer kernels, but
that is kind of intented to keep the logic KISS (because it's already
too complicated IMHO).
I investigated the allocation discrepancy and wrote the workaround while
we were still using stblinux-3.14.  Since then we've updated to
stblinux-4.1 and I've left the workaround enabled, but I haven't
investigated its interactions with the newer bmem mechanism.  I should
probably revisit this though, with stblinux-4.1 and stblinux-4.9, just
to make sure this macro is still useful.
Sounds good, let me know if there is something that does not seem quite
right, we could fix it.
[...]
In the v3 patch, I keep the FIT's RFS and DTB in-place.  This approach
eliminates the bmem/cma allocation discrepancies.  I compared bmem/cma
dmesg output for stblinux 3.14, 4.1 and 4.9, zImage and ITB builds, on
my eval board, and they're all the same for the same kernel version.
The only thing I noticed is that in 3.14 and 4.1 (zImage and ITB), the
first bmem region is:
768 MiB at 0x0000000010000000
whereas in 4.9 (zImage and ITB), it is:
760 MiB at 0x0000000010800000
This is booting with no kernel command line arguments, so I guess some
default may have changed between stblinux 4.1 and 4.9?
Thomas