I'm not really supporting the 2.4 drivers any more, but IMHO this
is really a BIOS problem. The BIOS should be able to recover the I2C
interface even if it is in the middle of a transaction.
Do you think this is a problem with the 2.6 driver? It doesn't have a
thread that does this, but does it from a timer interrupt.
-Corey
Brian Hamon (brhamon) wrote:
> I determined the root cause behind the problem I reported yesterday. I
> have tested this fix and found it to be effective. The conditions for
> encountering this problem are rare. I am providing the fix here for the
> benefit of others still using the ipmi_smb_intf driver on Linux-2.4.
>
> PROBLEM:
>
> On platforms where the BMC controls the reset line AND where the
> interface to the BMC is SMBus (I2C) AND where the kernel configuration
> includes "CONFIG_IPMI_SMB=y" (embedded, not modular) AND where the
> kernel version is 2.4.x, there is a 1 in 300 chance that the system will
> hang after displaying the message "Restarting system" on the console.
>
> The Linux-2.4 kernel does not call functions registered with the
> "module_exit" macro when MODULE is not defined (the driver is embedded).
> Even if it did, the original ipmi_smb_intf driver did not set up the
> call to clean up the driver.
>
> SOLUTION:
>
> Use the Linux-2.4 hack, register_reboot_notifier, modeled after the IDE
> driver. This kills the polling thread that can cause collisions at the
> I2C adapter for 10mS out of every 3000mS. With this thread gone, there
> is no chance of a collision preventing the BIOS reboot request message
> from getting to the BMC.
>
>
>
> DIFF:
>
> diff -rU3 linux-2.4.31/drivers/char/ipmi/ipmi_smb_intf.c
> linux-2.4.31.new/drivers/char/ipmi/ipmi_smb_intf.c
> --- linux-2.4.31/drivers/char/ipmi/ipmi_smb_intf.c Tue Jun 27
> 17:21:29 2006
> +++ linux-2.4.31.new/drivers/char/ipmi/ipmi_smb_intf.c Tue Jun 27
> 17:31:45 2006
> @@ -54,7 +54,9 @@
> #include <linux/i2c.h>
> #include <linux/ipmi_smi.h>
> #include <linux/init.h>
> -
> +#ifndef MODULE
> +#include <linux/reboot.h>
> +#endif
>
> #define IPMI_SMB_VERSION "37"
>
> @@ -1251,6 +1253,48 @@
> .dec_use = NULL,
> };
>
> +static void ipmi_cleanup_common(void)
> +{
> + int i;
> + int rv;
> +
> + if (!initialized)
> + return;
> +
> + for (i=0; i<MAX_SMB_BMCS; i++) {
> + cleanup_one_smb(smb_infos[i]);
> + }
> +
> + initialized = 0;
> +
> + rv = i2c_del_driver(&smb_i2c_driver);
> + if (!rv)
> + initialized = 0;
> +}
> +
> +#ifndef MODULE
> +static int ipmi_notify_reboot (struct notifier_block *this, unsigned
> long event, void *x)
> +{
> + switch (event) {
> + case SYS_HALT:
> + case SYS_POWER_OFF:
> + case SYS_RESTART:
> + break;
> + default:
> + return NOTIFY_DONE;
> + }
> +
> + ipmi_cleanup_common();
> + return NOTIFY_DONE;
> +}
> +
> +static struct notifier_block ipmi_notifier = {
> + ipmi_notify_reboot,
> + NULL,
> + 5
> +};
> +#endif
> +
> static __init int init_ipmi_smb(void)
> {
> int i;
> @@ -1281,6 +1325,9 @@
> if (!rv)
> initialized = 1;
>
> +#ifndef MODULE
> + register_reboot_notifier(&ipmi_notifier);
> +#endif
> return rv;
> }
> module_init(init_ipmi_smb);
> @@ -1288,21 +1335,7 @@
> #ifdef MODULE
> static __exit void cleanup_ipmi_smb(void)
> {
> - int i;
> - int rv;
> -
> - if (!initialized)
> - return;
> -
> - for (i=0; i<MAX_SMB_BMCS; i++) {
> - cleanup_one_smb(smb_infos[i]);
> - }
> -
> - initialized = 0;
> -
> - rv = i2c_del_driver(&smb_i2c_driver);
> - if (!rv)
> - initialized = 0;
> + ipmi_cleanup_common();
> }
> module_exit(cleanup_ipmi_smb);
> #else
>
>
> -----Original Message-----
> From: [EMAIL PROTECTED]
> [mailto:[EMAIL PROTECTED] On Behalf Of
> Brian Hamon (brhamon)
> Sent: Monday, June 26, 2006 2:49 PM
> To: [email protected]
> Subject: [Openipmi-developer] IPMI polling every 3 seconds not ending
> whendrivers integrated
>
> I am seeing a problem that is largely a product of the constraints of my
> environment. I am working to resolve it, but need a little help.
>
> First, my constraints. I am using an old kernel (2.4.30). The 2.4.31-v37
> patch files are working well for me. However, I've already run across
> problems that were resolved in later versions of the IPMI drivers in the
> 2.6 kernel. This may be one of those issues, and I'm sorry for wasting
> anyone's time if so.
>
> On my platforms, I am starting inside an initrd and pivot_root to the
> mass storage device. It works much better for me if the drivers that I
> need before and after the pivot_root are embedded into the kernel rather
> than built as loadable modules. IPMI is one of the drivers I need early
> in system initialization, so it is embedded in my kernel.
>
> Finally, the BMC on my platform is one with which I interface across the
> I2C bus (ipmi_smb_intf.o).
>
> The problems I encountered and solved are that the embedded drivers'
> init calls go into a linker segment and are allocated in the order in
> which the linker sees them. By patching the Makefiles, I was able to get
> the linker to see drivers/i2c before drivers/char/ipmi. This makes the
> I2C driver initialize before IPMI tries to use it to connect to the BMC
> over the I2C bus.
>
> Another problem had to do with the probing for an I2C BMC. My platform
> has SMBIOS tables identifying the BMC's I2C slave address. A bit of code
> walking through these tables provided the behavior I required. I later
> learned that this was something that had already been put into the 2.6
> kernel drivers.
>
> =====
>
> Now for my problem. I have seen that a small percentage of the time, the
> system will not reset itself. The platform is an Intel SE7520JR2
> mainboard with a National Semiconductor (Winbond) PC87431M mBMC. On this
> platform, the mBMC controls the system reset line. The AMIBIOS on this
> platform sends a reboot request to the mBMC (presumably an IPMI
> command).
>
> What I am seeing on the scope is a short message on the I2C bus sent
> every three seconds to the mBMC from the IPMI drivers. I am fairly
> certain this is ipmi_smb_intf polling for events from the mBMC (from
> smb_event_handler). What is odd is that this polling does not stop even
> after the kernel descends through the shutdown sequence to the
> sys_reboot service (INT 80h, service 88).
>
> The message takes about 10mS and repeats every three seconds. What we
> have observed is something on the order of 1 out of 300 reboots fail, so
> we think the IPMI driver is in the middle of manipulating the I2C
> control registers on the ICH5R when the BIOS tries to send the reboot
> request.
>
> I'm trying to figure out for sure if this polling is happening in the
> IPMI driver. If it is, why doesn't it stop when the driver is unloaded?
> If I can better understand the code sending the polling message, I
> should be able to fix it, but I need some guidance.
>
> It looks like stop_kthread in ipmi_smb_intf.c should stop the polling,
> but on my system the scope is indicating this is not happening.
>
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