From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mailman by lists.gnu.org with tmda-scanned (Exim 4.43) id 1M6JFk-0002BT-E4 for qemu-devel@nongnu.org; Tue, 19 May 2009 02:56:44 -0400 Received: from exim by lists.gnu.org with spam-scanned (Exim 4.43) id 1M6JFg-000294-Mp for qemu-devel@nongnu.org; Tue, 19 May 2009 02:56:44 -0400 Received: from [199.232.76.173] (port=48010 helo=monty-python.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1M6JFg-00028z-Ha for qemu-devel@nongnu.org; Tue, 19 May 2009 02:56:40 -0400 Received: from mx20.gnu.org ([199.232.41.8]:51125) by monty-python.gnu.org with esmtps (TLS-1.0:RSA_AES_256_CBC_SHA1:32) (Exim 4.60) (envelope-from ) id 1M6JFf-00008v-Q7 for qemu-devel@nongnu.org; Tue, 19 May 2009 02:56:40 -0400 Received: from mx2.redhat.com ([66.187.237.31]) by mx20.gnu.org with esmtp (Exim 4.60) (envelope-from ) id 1M6JFe-0003XE-Uh for qemu-devel@nongnu.org; Tue, 19 May 2009 02:56:39 -0400 Subject: Re: [Qemu-devel] [PATCH 1/4] Confine use of global rtc_state to PC CMOS functions References: <87zldtotvx.fsf@pike.pond.sub.org> From: Markus Armbruster Date: Tue, 19 May 2009 08:56:34 +0200 In-Reply-To: (Blue Swirl's message of "Tue\, 5 May 2009 19\:22\:33 +0300") Message-ID: <87pre5twbh.fsf@pike.pond.sub.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii List-Id: qemu-devel.nongnu.org List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Blue Swirl Cc: qemu-devel@nongnu.org Sorry for the sloooow respons, I was on vacation. Blue Swirl writes: > On 5/4/09, Markus Armbruster wrote: >> Blue Swirl writes: >> >> > On 4/30/09, Markus Armbruster wrote: >> >> Pass the state as argument to cmos_init() and cmos_init_hd(). >> >> cmos_init() still needs to save it in rtc_state for use by >> >> cmos_set_s3_resume(). >> > >> > pc.c could pass acpi an opaque handle (former rtc_state) at init or >> > acpi could export a function to set the handle, called by pc.c. Then >> > cmos_set_s3_resume could take a state parameter. >> >> >> We'd just move a global variable from pc.c to acpi.c, wouldn't we? >> Could you explain why that's a better place? > > No, acpi would only have an opaque pointer to the variable stored in > PIIX4PMState, the "owner" would still be pc.c. Okay, so we'd just move a global variable from pc.c into only instance of struct PIIX4PMState, referenced from a global variable in acpi.c. The fact that it becomes opaque in the process isn't much of an improvement, isn't it? >> Passing rtc_state to piix4_pm_init() doesn't work well for pcdt.c, >> because we'd have to pass it from RTC device to PIIX3 ACPI device >> somehow, creating one of those ugly "non-tree" device dependencies, >> i.e. one that doesn't follow device tree or interrupt tree edges. Your >> other idea (a function to set the handle) allows me to keep the two >> devices decoupled, provided I can set the handle even before >> piix4_pm_init(). > > Still one idea: a signal (qemu_irq) could be used to convey the s3 > resume condition. That may be another tree. Hmm. How does the hardware do it? Does it update CMOS all by itself? > Setting the handle before piix4_pm_init will fail if the handle is > going to be stored in PIIX4PMState, Correct. > but the setup can be reversed: > piix4_pm_init can call a function to get the handle. Where from? A global variable in pc.c? But then we create global state in acpi.c without reducing it in pc.c. In the context of pcdt.c: creates the same non-tree device dependency, only in the opposite direction.