On 10.12.2012, at 20:54, Henrik Rydberg wrote:
> Hi Guenter,
>
>> On Mon, Dec 10, 2012 at 09:51:35AM -0500, Gabriel L. Somlo wrote:
>>> The AppleSMC contains two char[32] keys, OSK0 and OSK1, which are not
>>> reported in the key count and index by default. These keys are used by
>>> the OS X boot sequence, and normally don't matter when running Linux.
>>>
>>> This patch creates a sysfs entry which reports the value of these keys
>>> as an ASCII string, to help emulators (such as QEMU) load OS X when
>>> running on genuine Apple hardware.
>>>
>>> Signed-off-by: Gabriel L. Somlo <so...@cmu.edu>
>>> ---
>>>
>>> For extra context: To boot OS X as a guest, QEMU must (among others)
>>> emulate the AppleSMC. To boot successfully, OS X insists on querying
>>> the (emulated) SMC for the value of OSK0 and OSK1. Currently, these
>>> values must be supplied on the QEMU command line as
>>>
>>> -device applesmc,osk="...concatenated values of OSK0 and OSK1..."
>>>
>>> With the availability of /sys/devices/platform/applesmc.768/osk, the
>>> emulated QEMU AppleSMC could acquire this string directly from the
>>> (Apple-manufactured) host machine.
>>>
>> Hmm ... this is a non-hwmon attribute which doesn't really belong into hwmon
>> in the first place ... like several other attributes in the same driver.
>>
>> So I'll leave it up to the maintainer to decide if we should accept it.
>> Henrik ?
>
> Indeed, the reaons against this patch are too many. I was just about
> to reply with the below:
>
> Gabriel,
>
> The OSK string seems constant accross machines, which renders the
> patch rather pointless, no? And even if the OSK differs between a
> couple of machines, the emulator could easily handle it gracefully.
The point is that the return value of the OSK is a copyrighted string, we can
not include in any other layer. The only way to make this legally savvy is to
read the key from the host.
>
> There are also some technical issues with the patch below, to keep in
> mind for future submissions.
Sigh - most of the comments below go back to earlier review from me. He
basically had a version almost exactly like what you're asking him to do :).
Funny how code style taste differs.
Alex
>
>> drivers/hwmon/applesmc.c | 18 ++++++++++++++++++
>> 1 files changed, 18 insertions(+), 0 deletions(-)
>>
>> diff --git a/drivers/hwmon/applesmc.c b/drivers/hwmon/applesmc.c
>> index b41baff..0c7cc71 100644
>> --- a/drivers/hwmon/applesmc.c
>> +++ b/drivers/hwmon/applesmc.c
>> @@ -1013,6 +1013,23 @@ static ssize_t applesmc_key_at_index_store(struct
>> device *dev,
>> return count;
>> }
>>
>> +static ssize_t applesmc_osk_show(struct device *dev,
>> + struct device_attribute *attr, char *sysfsbuf)
>> +{
>> + int fail;
>
> All other functions use 'ret' here...
>
>> +
>> + mutex_lock(&smcreg.mutex);
>> + fail = read_smc(APPLESMC_READ_CMD, "OSK0", sysfsbuf, 32) ||
>> + read_smc(APPLESMC_READ_CMD, "OSK1", sysfsbuf + 32, 32);
>
> The read function should propagate error messages, i.e., keep the
> return values here. And please read to buffers instead.
>
>> + mutex_unlock(&smcreg.mutex);
>> + if (fail)
>> + return -1;
>
> Return error here.
>
>> +
>> + sysfsbuf[64] = '\n';
>> + sysfsbuf[65] = '\0';
>> + return 65;
>
> A snprintf here, please.
>
>> +}
>> +
>> static struct led_classdev applesmc_backlight = {
>> .name = "smc::kbd_backlight",
>> .default_trigger = "nand-disk",
>> @@ -1027,6 +1044,7 @@ static struct applesmc_node_group info_group[] = {
>> { "key_at_index_type", applesmc_key_at_index_type_show },
>> { "key_at_index_data_length", applesmc_key_at_index_data_length_show },
>> { "key_at_index_data", applesmc_key_at_index_read_show },
>> + { "osk", applesmc_osk_show },
>
> Unfortunately this is not a good place to put random things going
> forward.
>
>> { }
>> };
>>
>> --
>> 1.7.7.6
>>
>
> Given the above issues together with the weak rationale for the patch
> in the first place, this patch will not be applied.
>
> Thanks.
> Henrik
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