Hi, For a while now I have been trying to debug an issue with Xen on the MacBook, doing this is part of my Summer of Code project to get Xen working properly on the Intel Mac. In case some of you don''t know, the MacBook is an Intel Core Duo based laptop from Apple, which lacks some legacy hardware. Xen (testing) works perfectly for me when starting it with "nosmp", however when not using it, it crashes while starting up the second core. There have been some bug report on this issue already. Below I will explain the problem in more detail and with some observations. I will be very grateful if someone can come up with ideas of how to fix this or give me some ideas that can lead to a solution. Not only Xen has this problem, but so has FreeBSD and NetBSD, so a solution will be beneficial to these projects as well. What happens is the following: The first core sends two IPI messages(INIT and STARTUP) to start the second core. When the second core is started, it notifies the first core of this so it can continue with the boot process. However, the second core is not started by these messages, the loop that waits for the second core times out, continues and Xen crashes. One strange thing is that Xen initializes the second core properly when you press a key on the keyboard after the IPIs are sent. I am expecting this interrupt somehow wakes up the second core so it can accept and process the IPIs. Because it is a laptop the second core is put in deep sleep mode to save power in case an OS does not use this core at all. But as I understand it, it should wake up when an INIT IPI arrives. The problems I am having with Xen can be reproduced with linux when booting with "acpi=ht", which means the ACPI interpreter is not started. Hopefully someone has some ideas how to deal with this issue and how to properly fix this. If you want more information or want me to test things, feel free to ask. Thanks, Marco _______________________________________________ Xen-devel mailing list Xen-devel@lists.xensource.com http://lists.xensource.com/xen-devel
> Xen (testing) works perfectly for me when starting it with "nosmp", > however when not using it, it crashes while starting up the second > core. There have been some bug report on this issue already.Marco, Have you tried -unstable? Some potentially relevant files have been updated. Also, exactly which version of Linux boots OK? Does 2.6.16 e.g. from the DemoCD? Thanks, Ian> Below I will explain the problem in more detail and with some > observations. I will be very grateful if someone can come up with > ideas of how to fix this or give me some ideas that can lead to a > solution. Not only Xen has this problem, but so has FreeBSD and > NetBSD, so a solution will be beneficial to these projects as well. > > What happens is the following: The first core sends two IPI > messages(INIT and STARTUP) to start the second core. When the second > core is started, it notifies the first core of this so it can continue > with the boot process. However, the second core is not started by > these messages, the loop that waits for the second core times out, > continues and Xen crashes. > > One strange thing is that Xen initializes the second core properly > when you press a key on the keyboard after the IPIs are sent. I am > expecting this interrupt somehow wakes up the second core so it can > accept and process the IPIs. Because it is a laptop the second core > is put in deep sleep mode to save power in case an OS does not use > this core at all. But as I understand it, it should wake up when an > INIT IPI arrives. > > The problems I am having with Xen can be reproduced with linux when > booting with "acpi=ht", which means the ACPI interpreter is not > started. > > Hopefully someone has some ideas how to deal with this issue and how > to properly fix this. If you want more information or want me to test > things, feel free to ask. > > Thanks, > Marco > > > _______________________________________________ > Xen-devel mailing list > Xen-devel@lists.xensource.com > http://lists.xensource.com/xen-devel_______________________________________________ Xen-devel mailing list Xen-devel@lists.xensource.com http://lists.xensource.com/xen-devel
"Ian Pratt" <m+Ian.Pratt@cl.cam.ac.uk> writes: Hi Ian,>> Xen (testing) works perfectly for me when starting it with "nosmp", >> however when not using it, it crashes while starting up the second >> core. There have been some bug report on this issue already. > > Marco, > Have you tried -unstable? Some potentially relevant files have been > updated.Yes, unstable has the same problem. Would you encourage development in unstable or testing?> Also, exactly which version of Linux boots OK? Does 2.6.16 e.g. from the > DemoCD?I have not tested the DemoCD because it still contains an unpatched GRUB. Because of that it doesn''t work with the Intel Mac. But I have tried linux 2.6.16 (self compiled), which works perfectly. Thanks, Marco _______________________________________________ Xen-devel mailing list Xen-devel@lists.xensource.com http://lists.xensource.com/xen-devel
> > Marco, > > Have you tried -unstable? Some potentially relevant files have been > > updated. > > Yes, unstable has the same problem. Would you encourage development > in unstable or testing?I''d go for -unstable. In reality, the stability is usually rather good.> > Also, exactly which version of Linux boots OK? Does 2.6.16 e.g. fromthe> > DemoCD? > > I have not tested the DemoCD because it still contains an unpatched > GRUB. Because of that it doesn''t work with the Intel Mac. > > But I have tried linux 2.6.16 (self compiled), which works perfectly.I might be worth trying the native kernel from the demo cd just to check it''s not a kernel config issue, but I admit it''s a bit of a long shot. Also, it might be good to test a similarly configed native 2.6.15/14/12 to see if any of them fail in the same way as Xen -- that would give us a big clue. Thanks, Ian _______________________________________________ Xen-devel mailing list Xen-devel@lists.xensource.com http://lists.xensource.com/xen-devel
"Ian Pratt" <m+Ian.Pratt@cl.cam.ac.uk> writes:>> > Marco, >> > Have you tried -unstable? Some potentially relevant files have been >> > updated. >> >> Yes, unstable has the same problem. Would you encourage development >> in unstable or testing? > > I''d go for -unstable. In reality, the stability is usually rather good.Sure.>> > Also, exactly which version of Linux boots OK? Does 2.6.16 e.g. from > the >> > DemoCD? >> >> I have not tested the DemoCD because it still contains an unpatched >> GRUB. Because of that it doesn''t work with the Intel Mac. >> >> But I have tried linux 2.6.16 (self compiled), which works perfectly. > > I might be worth trying the native kernel from the demo cd just to check > it''s not a kernel config issue, but I admit it''s a bit of a long shot.The problem is in Xen itself, if that is what you mean. I was a bit tired yesterday evening and for some reason I was thinking you meant a normal linux kernel. :)> Also, it might be good to test a similarly configed native 2.6.15/14/12 > to see if any of them fail in the same way as Xen -- that would give us > a big clue.I have been trying this, back to Linux 2.6.8. I will play a bit more with this, although it really looks like this being an ACPI related issue, for some reason ACPI is being able to wakeup the second core properly. -- Marco _______________________________________________ Xen-devel mailing list Xen-devel@lists.xensource.com http://lists.xensource.com/xen-devel
> >> I have not tested the DemoCD because it still contains an unpatched > >> GRUB. Because of that it doesn''t work with the Intel Mac. > >> > >> But I have tried linux 2.6.16 (self compiled), which worksperfectly.> > > > I might be worth trying the native kernel from the demo cd just tocheck> > it''s not a kernel config issue, but I admit it''s a bit of a longshot.> > The problem is in Xen itself, if that is what you mean. I was a bit > tired yesterday evening and for some reason I was thinking you meant a > normal linux kernel. :)There is a native kernel on the demo CD as well as the xen/linux one. They have very similar configs, so it''s often interesting to compare the behaviour of them.> > Also, it might be good to test a similarly configed native2.6.15/14/12> > to see if any of them fail in the same way as Xen -- that would giveus> > a big clue. > > I have been trying this, back to Linux 2.6.8. I will play a bit more > with this, although it really looks like this being an ACPI related > issue, for some reason ACPI is being able to wakeup the second core > properly.As you point out, things go wrong too early to be influenced by anything in xen/linux. However, trying booting different versions of native linux is useful as it will tell us when the issue was fixed in linux and hence identify what we need to do. Thanks, Ian _______________________________________________ Xen-devel mailing list Xen-devel@lists.xensource.com http://lists.xensource.com/xen-devel
Hi. I have xen running on my Macbook. The problem is cause by grub. When i start the xen entry in grub with the key "return" xen fails too boot. When i use the "Cursor key right" to start the xen entry xen boots fine. I used the atached patch against grub 0.97 for the Intel Macs. cu Edgar (gimli) Hucek Marco Gerards schrieb:> Hi, > > For a while now I have been trying to debug an issue with Xen on the > MacBook, doing this is part of my Summer of Code project to get Xen > working properly on the Intel Mac. In case some of you don''t know, > the MacBook is an Intel Core Duo based laptop from Apple, which lacks > some legacy hardware. > > Xen (testing) works perfectly for me when starting it with "nosmp", > however when not using it, it crashes while starting up the second > core. There have been some bug report on this issue already. > > Below I will explain the problem in more detail and with some > observations. I will be very grateful if someone can come up with > ideas of how to fix this or give me some ideas that can lead to a > solution. Not only Xen has this problem, but so has FreeBSD and > NetBSD, so a solution will be beneficial to these projects as well. > > What happens is the following: The first core sends two IPI > messages(INIT and STARTUP) to start the second core. When the second > core is started, it notifies the first core of this so it can continue > with the boot process. However, the second core is not started by > these messages, the loop that waits for the second core times out, > continues and Xen crashes. > > One strange thing is that Xen initializes the second core properly > when you press a key on the keyboard after the IPIs are sent. I am > expecting this interrupt somehow wakes up the second core so it can > accept and process the IPIs. Because it is a laptop the second core > is put in deep sleep mode to save power in case an OS does not use > this core at all. But as I understand it, it should wake up when an > INIT IPI arrives. > > The problems I am having with Xen can be reproduced with linux when > booting with "acpi=ht", which means the ACPI interpreter is not > started. > > Hopefully someone has some ideas how to deal with this issue and how > to properly fix this. If you want more information or want me to test > things, feel free to ask. > > Thanks, > Marco > > > _______________________________________________ > Xen-devel mailing list > Xen-devel@lists.xensource.com > http://lists.xensource.com/xen-devel >_______________________________________________ Xen-devel mailing list Xen-devel@lists.xensource.com http://lists.xensource.com/xen-devel
gimli <gimli@dark-green.com> writes: Hi Edgar, What a small world...> I have xen running on my Macbook. The problem is cause by grub. > When i start the xen entry in grub with the key "return" xen > fails too boot. When i use the "Cursor key right" to start > the xen entry xen boots fine. I used the atached patch against > grub 0.97 for the Intel Macs.Amazing, that works for me! I will have a look why this has some influence on SMP. The patch I have used for GRUB Legacy is a backport for enabling the A20 gate from GRUB 2. I have posted it on the bug-grub mailinglist in case you are interested and will commit it soon. Essentially it does almost the same as the one you are using. Thanks, Marco _______________________________________________ Xen-devel mailing list Xen-devel@lists.xensource.com http://lists.xensource.com/xen-devel