[U-Boot] [RFC PATCH v5 1/4] common: Convert ulong to phys_addr_t for image addresses

[Simon Glass <sjg@chromium.org>]

Hi York,

On 26 February 2016 at 10:22, york sun <york.sun@nxp.com> wrote:
> On 02/25/2016 03:05 PM, Wolfgang Denk wrote:
>> Dear York Sun,
>>
>> In message <1456439779-4792-2-git-send-email-york.sun@nxp.com> you wrote:
>>> When dealing with image addresses, ulong has been used. Some files
>>> are used by both host and target. It is OK for the target, but not
>>> always enough for host tools including mkimage. This patch replaces
>>> "ulong" with "phys_addr_t" to make sure addresses are correct for
>>> both the target and the host.
>>
>> You talk here about using "phys_addr_t"...
>>
>>> -                       ulong, ulong, ulong))images->ep;
>>> +                       ulong, ulong, ulong))(uintptr_t)images->ep;
>>
>> ...but here you use  uintptr_t  , hich is something different?
>>
>>> -            ulong, ulong, ulong))images->ep)(images->ft_addr,
>>> +            ulong, ulong, ulong))(uintptr_t)images->ep)(images->ft_addr,
>>
>> Ditto.
>>
>>> +    phys_addr_t os_data;
>>> +    ulong os_len;
>>>      void *data = NULL;
>>>      size_t len;
>>>      int ret;
>>> @@ -87,11 +89,10 @@ static int boot_prep_linux(bootm_headers_t *images)
>>>      if (images->legacy_hdr_valid) {
>>>              hdr = images->legacy_hdr_os;
>>>              if (image_check_type(hdr, IH_TYPE_MULTI)) {
>>> -                    ulong os_data, os_len;
>>
>> Why do you moe the declarations out of this block?  The variables are
>> only used within this block so there is no need for a wider scope?
>>
>>> -                    data = (void *)os_data;
>>> +                    data = (void *)(uintptr_t)os_data;
>>
>> This double cast looks scary to me, and you don;t explain it in the
>> commit message.  Why exactly is this needed?
>>
>>> -            cmd_line_dest = (void *)images->ep + COMMAND_LINE_OFFSET;
>>> +            cmd_line_dest = (void *)(uintptr_t)images->ep +
>>> +                            COMMAND_LINE_OFFSET;
>>
>> Ditto.
>>
>>> -    printf("Setup at %#08lx\n", images->ep);
>>> -    ret = setup_zimage((void *)images->ep, cmd_line_dest,
>>> +    printf("Setup at %#08" PRIpa "\n", images->ep);
>>
>> This is really ugly...
>>
>>> +    ret = setup_zimage((void *)(uintptr_t)images->ep, cmd_line_dest,
>>
>> See before.
>>
>>> -    debug("## Transferring control to Linux (at address %08lx, kernel %08lx) ...\n",
>>> +    debug("## Transferring control to Linux (at address %#08" PRIpa
>>> +          ", kernel %#08" PRIpa ") ...\n",
>>
>> See before...
>>
>>> -            debug("*  kernel: cmdline image address = 0x%08lx\n",
>>> -                    images->ep);
>>> +            debug("*  kernel: cmdline image address = %#08" PRIpa "\n",
>>> +                  images->ep);
>>
>> Ditto.  etc. etc.
>>
>>> +    /*
>>> +     * In this function, data is decalred as phys_addr_t type.
>>
>> s/decalred/declared/
>>
>>> +     * On some systems (eg. ARM, PowerPC) phys_addr_t can be
>>> +     * "unsigned long", or "unsigned long long", depending on
>>> +     * CONFIG_PHYS_64BIT.  It is safe to cast 64-bit phys_addr_t
>>> +     * to 32-bit pointer for image handling because the actual
>>> +     * address the image is loaded is within 32-bit space.
>>
>> Who guarantees that?
>>
>>> -            data = (ulong)fit_data;
>>> +            data = (phys_addr_t)(uintptr_t)fit_data;
>>
>> This double cast looks strange to me.  Why is it needed?
>>
>>> -                            void *from = (void *)data;
>>> +                            void *from = (void *)(uintptr_t)data;
>>
>> Ditto.
>>
>>> -                    memmove((char *) dest, (char *)data, len);
>>> +                    memmove((char *)dest, (char *)(uintptr_t)data, len);
>>
>> Ditto. etc. etc.
>>
>>
>> All these double casts look somewhat wrong to me.  Why are they
>> needed?
>
> Dear Wolfgang,
>
> I can use some serious help here. What I am really trying to achieve is the last
> two patches in this set. I didn't want to use replace ulong with phys_addr_t. I
> am not proud with the change I proposed, but I didn't come up with a smarter
> solution. My specific trouble is to build ARMv8 targets on 32-bit Ubuntu host.
> Some code is shared between the target and host tool (mkimage). I started from
> small changes, but it gets wider and wider when I tried to get rid of the
> compiling warnings.
>
> York
>

I suggest just documenting it better with comments and in the commit
message. It's mostly the same comment I made.

One concern is that if you cast to uintptr_t on a 32-bit host machine,
won't you end up dropping the top 32 bits?

Regards,
Simon