[U-Boot] [RFC PATCH] itest: allow map_physmem to return 0 in limited cases

[Simon Glass]

On 29 January 2016 at 16:10, Stephen Warren <swarren at wwwdotorg.org> wrote:
> From: Stephen Warren <swarren at nvidia.com>
>
> 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 at nvidia.com>
> ---
> Another approach would be to fix the scripts generated by t-u-f to use
> some other address, e.g. address 4. However, I think itest should work
> on any legal address in RAM?
>
>  common/cmd_itest.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)

Acked-by: Simon Glass <sjg at chromium.org>

This seems OK. I don't think we care about the case where sandbox
can't get to its memory. But if you want to improve this, I'd favour a
new function that returns an error code and puts the return pointer in
a parameter, like

int map_physmem_ptr(phys_addr_t paddr, ulong len, ulong flags, void **ptrp)

>
> diff --git a/common/cmd_itest.c b/common/cmd_itest.c
> index 91ae5c2704c8..fb4d797e43d7 100644
> --- a/common/cmd_itest.c
> +++ b/common/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;
>                 }
> --
> 2.7.0
>

Regards,
Simon