From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Rafael J. Wysocki" Subject: Re: 2.6.19: ACPI reports AC not present after resume from STD Date: Sun, 25 Feb 2007 19:58:36 +0100 Message-ID: <200702251958.37315.rjw@sisk.pl> References: <8E389A5F2FEABA4CB1DEC35A25CB39CE82FE9F@mssmsx411> <200702251151.12107.rjw@sisk.pl> <200702252014.26110.arvidjaar@mail.ru> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: In-Reply-To: <200702252014.26110.arvidjaar@mail.ru> Content-Disposition: inline Sender: linux-acpi-owner@vger.kernel.org To: Andrey Borzenkov Cc: "Lebedev, Vladimir P" , "Karasyov, Konstantin A" , linux-acpi@vger.kernel.org, linux-kernel@vger.kernel.org, linux-pm@lists.osdl.org, Andrew Morton List-Id: linux-pm@vger.kernel.org On Sunday, 25 February 2007 18:14, Andrey Borzenkov wrote: > On =D0=92=D0=BE=D1=81=D0=BA=D1=80=D0=B5=D1=81=D0=B5=D0=BD=D1=8C=D0=B5= 25 =D1=84=D0=B5=D0=B2=D1=80=D0=B0=D0=BB=D1=8F 2007, Rafael J. Wysocki = wrote: > > On Sunday, 25 February 2007 11:37, Andrey Borzenkov wrote: > > > On =D0=92=D0=BE=D1=81=D0=BA=D1=80=D0=B5=D1=81=D0=B5=D0=BD=D1=8C=D0= =B5 25 =D1=84=D0=B5=D0=B2=D1=80=D0=B0=D0=BB=D1=8F 2007, Rafael J. Wysoc= ki wrote: > > > > On Sunday, 25 February 2007 00:26, Andrey Borzenkov wrote: > > > > > On =D0=A1=D1=83=D0=B1=D0=B1=D0=BE=D1=82=D0=B0 24 =D1=84=D0=B5= =D0=B2=D1=80=D0=B0=D0=BB=D1=8F 2007, Rafael J. Wysocki wrote: > > > > > > Hi, > > > > > > > > > > > > On Saturday, 24 February 2007 10:55, Andrey Borzenkov wrote= : > > > > > > > On =D0=92=D1=82=D0=BE=D1=80=D0=BD=D0=B8=D0=BA 13 =D1=84=D0= =B5=D0=B2=D1=80=D0=B0=D0=BB=D1=8F 2007, Andrey Borzenkov wrote: > > > > > > > > On =D0=A7=D0=B5=D1=82=D0=B2=D0=B5=D1=80=D0=B3 07 =D0=B4= =D0=B5=D0=BA=D0=B0=D0=B1=D1=80=D1=8F 2006, Lebedev, Vladimir P wrote: > > > > > > > > > Please register new bug, attach acpidump and dmesg. > > > > > > > > > > > > > > > > http://bugzilla.kernel.org/show_bug.cgi?id=3D7995 > > > > > > > > > > > > > > > > regards > > > > > > > > > > > > > > Well, this starts looking like ACPI is not at fault. > > > > > > > > > > > > > > When reporting AC state ACPI just reads contents of syste= m memory > > > > > > > (I presume it gets updated by BIOS/ACPI when AC state cha= nges). > > > > > > > It looks like this memory area is restored during resume = from > > > > > > > STD. I updated mentioned bug report with more detailed > > > > > > > description. Now if someone could suggest a way to catch = if > > > > > > > specific physical address gets saved/restored this would = finally > > > > > > > explain it. > > > > > > > > > > > > First, if you want the reserved memory areas to be left alo= ne by > > > > > > swsusp, you need to mark them as 'nosave'. On x86_64 this = is done > > > > > > by the function e820_mark_nosave_range() in > > > > > > arch/x86_64/kernel/e820.c that can be ported to i386 with n= o > > > > > > problems. However, we haven't found that very useful, so f= ar, > > > > > > since no one has ever reported any problems with the curren= t > > > > > > approach, which is to save and restore them. > > > > > > > > > > Well, the following proof of concept patch fixes this issue f= or me. > > > > > Please notice that original version of e820_mark_nosave_range= () could > > > > > fail to exclude some areas due to alignment issues (exactly w= hat > > > > > happened to me on first try) so it still can explain your pro= blem > > > > > too. > > > > > > > > Great job, thanks for the patch! It looks good, so I'm going t= o > > > > forward it for merging. > > > > > > Please no; I'm currently testing slightly more polished version; = I will > > > send it later. > > > > OK > > > > > Could anybody explain (or give pointer to) what happens which reg= ion that > > > is not page-aligned? In particular, the very first one: > > > > > > BIOS-e820: 0000000000000000 - 000000000009fc00 (usable) > > > BIOS-e820: 000000000009fc00 - 00000000000a0000 (reserved) > > > > > > Will the kernel allocate partial page (how?) or will the kernel i= gnore > > > last (first) incomplete page? In the former case how those incomp= lete > > > pages can be detected? > > > > Well, on x86_64, if I understand e820_register_active_regions() cor= rectly, > > the partial pages won't be registered. > > >=20 > It appears that for low memory kernel will ignore incomplete pages fo= r sure. I=20 > hope it does the same for high memory - but for now I just throw this= in and=20 > pray :) You don't need to do this for highmem, because swsusp won't save reserv= ed highmem pages anyway. > This also significantly simplifies patch.=20 >=20 > As this touches quite sensitive field, I Cc Andrew - if he considers = this=20 > appropriate for mm; or would you do it as part of your tree? Also he = probably=20 > can easily clarify memory allocation questions :p The patch looks good, but the changelog does not. First, AFAICT, the x= 86_64 code doesn't touch anything outside the e820 map. Why do you think it = does? Second, it is not true that the region in question is at 0xee00 on x86_= 64. At least on my box it's above the end of RAM. I think the x86_64 version is correct too. Greetings, Rafael - To unsubscribe from this list: send the line "unsubscribe linux-acpi" i= n the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html