itest: allow map_physmem to return 0 in limited cases

On some systems, RAM starts at address 0. If the user executes itest
against address 0 on such a system, it will call map_physmem(0, ...)
which will return 0 back; mapping only changes the address on sandbox.
This causes itest to believe map_physmem() has failed, and hence fails
the comparison.

Fix itest so that it allows map_physmem() to return 0 /if/ the orignal
address passed to it was also 0.

This fixes "tegra-uboot-flasher flash" on Tegra20.

This has the disadvantage that on sandbox, failed mapping attempts for
address 0 are not detected. Instead, should the code only call
map_physmem() on sandbox? Or, should map_physmem() return its error status
some other way. Or, should the special case only be allowed on systems
where the base of RAM is 0 somehow?

Fixes: 7861204c9af7 ("itest: make memory access work under sandbox")
Signed-off-by: Stephen Warren <swarren@nvidia.com>

diff --git a/cmd/itest.c b/cmd/itest.c
index 91ae5c2704c882be8d4457d67d5f8488b19d2f1c..fb4d797e43d78b56b4a466a7d086bfcdb20cdf14 100644 (file)
--- a/cmd/itest.c
+++ b/cmd/itest.c
@@ -59,7 +59,7 @@ static long evalexp(char *s, int w)
        if (s[0] == '*') {
                addr = simple_strtoul(&s[1], NULL, 16);
                buf = map_physmem(addr, w, MAP_WRBACK);
-               if (!buf) {
+               if (!buf && addr) {
                        puts("Failed to map physical memory\n");
                        return 0;
                }