From: "Michael S. Tsirkin" <mst@redhat.com>
To: "Gabriel L. Somlo" <somlo@cmu.edu>
Cc: gregkh@linuxfoundation.org, robh+dt@kernel.org,
pawel.moll@arm.com, mark.rutland@arm.com,
ijc+devicetree@hellion.org.uk, galak@codeaurora.org,
arnd@arndb.de, lersek@redhat.com, ralf@linux-mips.org,
rmk+kernel@arm.linux.org.uk, eric@anholt.net,
hanjun.guo@linaro.org, zajec5@gmail.com, sudeep.holla@arm.com,
agross@codeaurora.org, linux-api@vger.kernel.org,
linux-kernel@vger.kernel.org, devicetree@vger.kernel.org,
qemu-devel@nongnu.org, imammedo@redhat.com,
peter.maydell@linaro.org, leif.lindholm@linaro.org,
ard.biesheuvel@linaro.org, pbonzini@redhat.com,
kraxel@redhat.com, ehabkost@redhat.com, luto@amacapital.net,
stefanha@gmail.com, revol@free.fr, matt@codeblueprint.co.uk,
rth@twiddle.net
Subject: Re: [PATCH v8 1/4] firmware: introduce sysfs driver for QEMU's fw_cfg device
Date: Sun, 21 Feb 2016 15:10:30 +0200 [thread overview]
Message-ID: <20160221150904-mutt-send-email-mst@redhat.com> (raw)
In-Reply-To: <20160221130614.GA4511@GLSMBP.INI.CMU.EDU>
On Sun, Feb 21, 2016 at 08:06:17AM -0500, Gabriel L. Somlo wrote:
>
> >
> > > +#if !(defined(FW_CFG_CTRL_OFF) && defined(FW_CTRL_DATA_OFF))
> > > +# if (defined(CONFIG_ARM) || defined(CONFIG_ARM64))
> > > +# define FW_CFG_CTRL_OFF 0x08
> > > +# define FW_CFG_DATA_OFF 0x00
> > > +# elif (defined(CONFIG_PPC_PMAC) || defined(CONFIG_SPARC32)) /* ppc/mac,sun4m */
> > > +# define FW_CFG_CTRL_OFF 0x00
> > > +# define FW_CFG_DATA_OFF 0x02
> > > +# elif (defined(CONFIG_X86) || defined(CONFIG_SPARC64)) /* x86, sun4u */
> > > +# define FW_CFG_CTRL_OFF 0x00
> > > +# define FW_CFG_DATA_OFF 0x01
> > > +# else
> > > +# warning "QEMU FW_CFG may not be available on this architecture!"
> > > +# define FW_CFG_CTRL_OFF 0x00
> > > +# define FW_CFG_DATA_OFF 0x01
> >
> > Better not try hacks like this, they are hard
> > to support down the road. Please only list what is tested and
> > actually exposed by QEMU.
>
> I was looking for a standard way to advertise register offsets within
> the ioport or mmio region assigned to fw_cfg, but right now the answer
> is "there isn't one", and "register offsets are an arch specific
> detail". As such, the only reasonable way I saw was to copy the same
> values used in the QEMU source.
>
> See also:
> https://lists.gnu.org/archive/html/qemu-devel/2015-11/msg05037.html
>
> Thanks much,
> --Gabriel
My point is you don't know what will qemu do on these
other arches which do not at the moment have fw cfg.
So don't try to guess!
--
MST
next prev parent reply other threads:[~2016-02-21 17:59 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-01-28 14:23 [PATCH v8 0/4] SysFS driver for QEMU " Gabriel L. Somlo
2016-01-28 14:23 ` [PATCH v8 1/4] firmware: introduce sysfs driver for QEMU's " Gabriel L. Somlo
2016-02-21 8:30 ` Michael S. Tsirkin
2016-02-21 13:06 ` Gabriel L. Somlo
2016-02-21 13:10 ` Michael S. Tsirkin [this message]
2016-02-21 17:20 ` Gabriel L. Somlo
2016-02-21 13:14 ` Michael S. Tsirkin
2016-02-22 20:14 ` Michael S. Tsirkin
2016-02-22 20:26 ` Gabriel L. Somlo
2016-02-23 5:07 ` Michael S. Tsirkin
2016-02-23 13:47 ` Gabriel L. Somlo
2016-02-23 14:14 ` Michael S. Tsirkin
2016-02-24 0:03 ` Gabriel L. Somlo
2016-01-28 14:23 ` [PATCH v8 2/4] kobject: export kset_find_obj() for module use Gabriel L. Somlo
2016-02-07 7:24 ` Greg KH
2016-02-07 14:27 ` Gabriel L. Somlo
2016-01-28 14:23 ` [PATCH v8 3/4] firmware: create directory hierarchy for sysfs fw_cfg entries Gabriel L. Somlo
2016-01-28 14:23 ` [PATCH v8 4/4] devicetree: update documentation for fw_cfg ARM bindings Gabriel L. Somlo
2016-02-03 22:47 ` [PATCH v8 0/4] SysFS driver for QEMU fw_cfg device Matt Fleming
2016-02-10 1:38 ` Greg KH
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