Hi, I configured serial console on my system today by adding com1=115200,8n1 console=vga,com1 to my kernel line in grub: title Xen 3.2.1 / Linux 2.6.21-xen root (hd0,0) kernel /xen.gz vtd=1 com1=115200,8n1 console=vga,com1 module /vmlinuz-2.6.21-xen root=/dev/sda2 The xen bootup messages are logged to the serial and vga consoles, and initially the kernel messages are also displayed, but it stops after "Freeing unused kernel memory: 208k freed" I am able to login through agetty on ttyS0, so the serial port is still working, it just stops logging after that line. CONFIG_FB is disabled, I read that sometimes framebuffer console can break serial console. CONFIG_VGA_CONSOLE=y CONFIG_VGACON_SOFT_SCROLLBACK=y CONFIG_VGACON_SOFT_SCROLLBACK_SIZE=256 Andy _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
On Thu, Sep 25, 2008 at 3:16 PM, Andrew Lyon <andrew.lyon@gmail.com> wrote:> Hi, > > I configured serial console on my system today by adding > com1=115200,8n1 console=vga,com1 to my kernel line in grub: > > title Xen 3.2.1 / Linux 2.6.21-xen > root (hd0,0) > kernel /xen.gz vtd=1 com1=115200,8n1 console=vga,com1 > module /vmlinuz-2.6.21-xen root=/dev/sda2 > > The xen bootup messages are logged to the serial and vga consoles, and > initially the kernel messages are also displayed, but it stops after > "Freeing unused kernel memory: 208k freed" > > I am able to login through agetty on ttyS0, so the serial port is > still working, it just stops logging after that line. > > CONFIG_FB is disabled, I read that sometimes framebuffer console can > break serial console. > > CONFIG_VGA_CONSOLE=y > CONFIG_VGACON_SOFT_SCROLLBACK=y > CONFIG_VGACON_SOFT_SCROLLBACK_SIZE=256 > > Andy >It seems that the serial console is completely dead after "Freeing unused kernel memory: 208k freed", I cannot access the sysreq commands and which I need to debug a lockup problem. Is there something wrong with the way I have configured the serial console? Andy _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
"Andrew Lyon" <andrew.lyon@gmail.com> writes:> I configured serial console on my system today by adding > com1=115200,8n1 console=vga,com1 to my kernel line in grub: > > title Xen 3.2.1 / Linux 2.6.21-xen > root (hd0,0) > kernel /xen.gz vtd=1 com1=115200,8n1 console=vga,com1 > module /vmlinuz-2.6.21-xen root=/dev/sda2 > > The xen bootup messages are logged to the serial and vga consoles, and > initially the kernel messages are also displayed, but it stops after > "Freeing unused kernel memory: 208k freed"it appears the problem is that you have told Xen to use the serial console, but you have not told Linux to use the serial console... this is consistent with Xen outputting to the serial console, then a quiet serial console while linux boots, then a working getty. here is what my grub config looks like on my headless CentOS/Xen boxes: serial --unit=0 --speed=115200 --word=8 --parity=no --stop=1 terminal serial console title CentOS (2.6.18-53.1.21.el5xen) root (hd0,0) kernel /boot/xen.gz-2.6.18-53.1.21.el5 dom0_mem=512M com1=115200,8n1 module /boot/vmlinuz-2.6.18-53.1.21.el5xen selinux=0 ro root=/dev/md0 console=ttyS0,115200n8 module /boot/initrd-2.6.18-53.1.21.el5xen.img the part you are missing is the console=ttyS0,115200n8 on the module line for the Linux kernel. add that and I bet it will work. _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
"Andrew Lyon" <andrew.lyon@gmail.com> writes:> It seems that the serial console is completely dead after "Freeing > unused kernel memory: 208k freed"That''s strange indeed. What appears on the VGA console after this line? (If you can scroll back via Shift+PgUp.)> I cannot access the sysreq commands and which I need to debug a > lockup problem.I''ve never managed to get the break through the hypervisor on a serial port. That means no sysrq for dom0. That and the lack of flow control make the Xen serial support unprofessional. Those would be my wishes for 3.4... :)> Is there something wrong with the way I have configured the serial > console?As you can see some kernel messages, it looks like you configured the kernel console, contrary to what your config shows... -- Regards, Feri. _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
On Sat, Sep 27, 2008 at 1:57 AM, Luke S Crawford <lsc@prgmr.com> wrote:> "Andrew Lyon" <andrew.lyon@gmail.com> writes: >> I configured serial console on my system today by adding >> com1=115200,8n1 console=vga,com1 to my kernel line in grub: >> >> title Xen 3.2.1 / Linux 2.6.21-xen >> root (hd0,0) >> kernel /xen.gz vtd=1 com1=115200,8n1 console=vga,com1 >> module /vmlinuz-2.6.21-xen root=/dev/sda2 >> >> The xen bootup messages are logged to the serial and vga consoles, and >> initially the kernel messages are also displayed, but it stops after >> "Freeing unused kernel memory: 208k freed" > > it appears the problem is that you have told Xen to use the serial console, but > you have not told Linux to use the serial console... this is consistent with > Xen outputting to the serial console, then a quiet serial console while > linux boots, then a working getty.You are correct, I did not tell linux about the serial console, but some of the linux kernel messages did appear on the serial console so I assumed that it had been auto detected, I tried adding console=ttyS0,1152008n1 to the linux kernel parameters and that made the serial console work correctly, but I noticed in the dmesg that the Xen console is detected as xvc0 "console [xvc0] enabled" and there was no ttyS0 device on which to run a getty, so I changed the device to xvc0 for both the kernel console and the getty and that also works. Thanks for your help Andy> > here is what my grub config looks like on my headless CentOS/Xen boxes: > > > serial --unit=0 --speed=115200 --word=8 --parity=no --stop=1 > terminal serial console > > title CentOS (2.6.18-53.1.21.el5xen) > root (hd0,0) > kernel /boot/xen.gz-2.6.18-53.1.21.el5 dom0_mem=512M com1=115200,8n1 > module /boot/vmlinuz-2.6.18-53.1.21.el5xen selinux=0 ro root=/dev/md0 console=ttyS0,115200n8 > module /boot/initrd-2.6.18-53.1.21.el5xen.img > > > > the part you are missing is the console=ttyS0,115200n8 on the module line > for the Linux kernel. add that and I bet it will work. >_______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
On Sat, Sep 27, 2008 at 7:04 PM, Ferenc Wagner <wferi@niif.hu> wrote:> "Andrew Lyon" <andrew.lyon@gmail.com> writes: > >> It seems that the serial console is completely dead after "Freeing >> unused kernel memory: 208k freed" > > That''s strange indeed. What appears on the VGA console after this > line? (If you can scroll back via Shift+PgUp.) > >> I cannot access the sysreq commands and which I need to debug a >> lockup problem. > > I''ve never managed to get the break through the hypervisor on a serial > port. That means no sysrq for dom0. That and the lack of flow > control make the Xen serial support unprofessional. Those would be my > wishes for 3.4... :)Indeed mine too, I''ve been getting random lockups on all 3 of the machines I''ve tested Xen on, with kernel 2.6.18 xensource, 2.6.21 gentoo and 2.6.25 suse, without sysrq I don''t have any hope of debugging the lockups at all and I will probably end up abandoning Xen which will be a real shame, I really like the performance and features and I really dont want to go back to vmware now. Andy> >> Is there something wrong with the way I have configured the serial >> console? > > As you can see some kernel messages, it looks like you configured the > kernel console, contrary to what your config shows... > -- > Regards, > Feri. >_______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
On Mon, Sep 29, 2008 at 4:17 PM, Andrew Lyon <andrew.lyon@gmail.com> wrote:> On Sat, Sep 27, 2008 at 7:04 PM, Ferenc Wagner <wferi@niif.hu> wrote: >> "Andrew Lyon" <andrew.lyon@gmail.com> writes: >> >>> It seems that the serial console is completely dead after "Freeing >>> unused kernel memory: 208k freed" >> >> That''s strange indeed. What appears on the VGA console after this >> line? (If you can scroll back via Shift+PgUp.) >> >>> I cannot access the sysreq commands and which I need to debug a >>> lockup problem. >> >> I''ve never managed to get the break through the hypervisor on a serial >> port. That means no sysrq for dom0. That and the lack of flow >> control make the Xen serial support unprofessional. Those would be my >> wishes for 3.4... :) > > Indeed mine too, I''ve been getting random lockups on all 3 of the > machines I''ve tested Xen on, with kernel 2.6.18 xensource, 2.6.21 > gentoo and 2.6.25 suse, without sysrq I don''t have any hope of > debugging the lockups at all and I will probably end up abandoning Xen > which will be a real shame, I really like the performance and features > and I really dont want to go back to vmware now. > > AndySysrq works!, you need to use ctrl+o instead of break, i.e. ctrl+o, <command>. Andy> >> >>> Is there something wrong with the way I have configured the serial >>> console? >> >> As you can see some kernel messages, it looks like you configured the >> kernel console, contrary to what your config shows... >> -- >> Regards, >> Feri. >> >_______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
"Andrew Lyon" <andrew.lyon@gmail.com> writes:> Sysrq works!, you need to use ctrl+o instead of break, i.e. ctrl+o, <command>.Way cool! Thanks a lot for sharing this info! I''m curious, how did you find out? -- Thanks, Feri. _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
On Mon, Sep 29, 2008 at 4:59 PM, Ferenc Wagner <wferi@niif.hu> wrote:> "Andrew Lyon" <andrew.lyon@gmail.com> writes: > >> Sysrq works!, you need to use ctrl+o instead of break, i.e. ctrl+o, <command>. > > Way cool! Thanks a lot for sharing this info! I''m curious, how did > you find out? > -- > Thanks, > Feri. >In console.c line 338: if (buf[i] == ''\x0f'') { /* ^O */ http://xenbits.xensource.com/linux-2.6.18-xen.hg?file/52f308b17bae/drivers/xen/console/console.c Andy _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users