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

[Simon Glass]

On 6 February 2016 at 13:29, Simon Glass <sjg at chromium.org> wrote:
> 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)
>

Applied to u-boot-dm, thanks!

>>
>> 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