linux-kernel - Re: [PATCH 15/16] platform/x86: wmi-mof: New driver to expose embedded WMI MOF metadata

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Date:   Sat, 27 May 2017 13:14:15 +0200
From:   Pali Rohár <pali.rohar@...il.com>
To:     Darren Hart <dvhart@...radead.org>
Cc:     platform-driver-x86@...r.kernel.org,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Andy Lutomirski <luto@...nel.org>,
        Andy Lutomirski <luto@...capital.net>,
        Mario Limonciello <mario_limonciello@...l.com>,
        Rafael Wysocki <rjw@...ysocki.net>,
        linux-kernel@...r.kernel.org, linux-acpi@...r.kernel.org
Subject: Re: [PATCH 15/16] platform/x86: wmi-mof: New driver to expose embedded WMI MOF metadata

Hi! Note that in WMI is stored binary MOF (BMOF; .bmf file; compiled 
MOF), not ordinary MOF data which are plain text. So maybe it could make 
sense to include "B" into name of sysfs entry? Or not? (Just suggestion)

On Saturday 27 May 2017 07:31:29 Darren Hart wrote:
> From: Andy Lutomirski <luto@...nel.org>
> 
> Quite a few laptops (and maybe servers?) have embedded WMI MOF

Not "a few", but "lots of" :-)

> metadata. I think that Samba has tools to interpret it, but there is
> currently no interface to get the data in the first place.

No, there is no non-ms-windows tool for interpreting those binary MOF 
(BMF) data yet.

> +	priv->mofdata = wmidev_block_query(wdev, 0);
> +	if (!priv->mofdata) {
> +		dev_warn(&wdev->dev, "failed to read MOF\n");
> +		return -EIO;
> +	}
> +
> +	if (priv->mofdata->type != ACPI_TYPE_BUFFER) {
> +		dev_warn(&wdev->dev, "MOF is not a buffer\n");
> +		ret = -EIO;
> +		goto err_free;
> +	}

Are not those problems fatal for driver and therefore dev_err() better?

> +	sysfs_bin_attr_init(&priv->mof_bin_attr);
> +	priv->mof_bin_attr.attr.name = "mof";
> +	priv->mof_bin_attr.attr.mode = 0400;

0400 means to be readable only by root? Is there then reason why normal 
user should not be able to read it?

-- 
Pali Rohár
pali.rohar@...il.com

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