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Date:      Sun, 9 Feb 2020 21:12:17 -0800
From:      Mark Millard <marklmi@yahoo.com>
To:        freebsd-arm <freebsd-arm@freebsd.org>, "jeff@freebsd.org" <jeff@FreeBSD.org>, Kyle Evans <kevans@FreeBSD.org>
Subject:   RPi4's memreserve use in fdt not handled by aarch64 fdt_get_reserved_mem (called via its initarm)
Message-ID:  <DF1349C0-ACFA-4FA9-9AC2-507BD0DBB0DE@yahoo.com>
References:  <DF1349C0-ACFA-4FA9-9AC2-507BD0DBB0DE.ref@yahoo.com>
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aarch64 seems to be ignoring the RPi4B's memreserve use.

My hypothesis is that head -r356776 and later are
allocating RAM areas that overlap with the
memreserve area.

1st see separate submittals about the live dts text reported
by fdt print in u-boot on the example RPi4B 4 GiByte machine:

https://lists.freebsd.org/pipermail/freebsd-arm/2020-February/021207.html
https://lists.freebsd.org/pipermail/freebsd-arm/2020-February/021205.html

Then:

aarch64's initarm uses fdt_get_reserved_mem and not
fdt_get_reserved_regions. So, looking at what that
implies:

int
fdt_get_reserved_mem(struct mem_region *reserved, int *mreserved)
{
        pcell_t reg[FDT_REG_CELLS];
        phandle_t child, root;
        int addr_cells, size_cells;
        int i, rv;

        root = OF_finddevice("/reserved-memory");
        if (root == -1) {
                return (ENXIO);
        }
. . . (I'll not list it all to show the lack of
memreserve handling) . . .

This does not check for and handle memreserve. 

By contrast armv7 and armv6 each have an initarm
that uses fdt_get_reserved_regions and that in
turn has:

int
fdt_get_reserved_regions(struct mem_region *mr, int *mrcnt)
{
        pcell_t reserve[FDT_REG_CELLS * FDT_MEM_REGIONS];
        pcell_t *reservep;
        phandle_t memory, root;
        int addr_cells, size_cells;
        int i, res_len, rv, tuple_size, tuples;

        root = OF_finddevice("/");
        memory = OF_finddevice("/memory");
        if (memory == -1) {
                rv = ENXIO;
                goto out;
        }

        if ((rv = fdt_addrsize_cells(OF_parent(memory), &addr_cells,
            &size_cells)) != 0)
                goto out;

        if (addr_cells > 2) {
                rv = ERANGE;
                goto out;
        }
  
        tuple_size = sizeof(pcell_t) * (addr_cells + size_cells);
 
        res_len = OF_getproplen(root, "memreserve");
        if (res_len <= 0 || res_len > sizeof(reserve)) {
                rv = ERANGE;
                goto out;
        }
 
        if (OF_getprop(root, "memreserve", reserve, res_len) <= 0) {
                rv = ENXIO;
                goto out;
        }
. . .

So this handles memreserve but not /reserved-memory .

It appears that for the RPi4B's the 32-bit "normal use"
has lead to aarch64 having memreserve instead of
/reserved-memory .


===
Mark Millard
marklmi at yahoo.com
( dsl-only.net went
away in early 2018-Mar)

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