the patch is good.
I tried LinuxBIOS with kexec.
without this patch: I need to disable acpi in kernel. otherwise the kernel with acpi support can boot the second kernel, but the second kernel will hang after
time.c: Using 14.318180 MHz HPET timer. time.c: Detected 2197.663 MHz processor. Console: colour VGA+ 80x25 Dentry cache hash table entries: 131072 (order: 8, 1048576 bytes) Inode-cache hash table entries: 65536 (order: 7, 524288 bytes) Memory: 1009152k/1048576k available (2967k kernel code, 39036k reserved, 1186k )
YH
On 1/2/06, Vivek Goyal vgoyal@in.ibm.com wrote:
Hi Andi,
Can you please include the following patch. This patch has already been pushed by Andrew.
http://kernel.org/pub/linux/kernel/people/akpm/patches/2.6/2.6.15-rc5/2.6.15...
This patch is regarding remembering at boot up time where i8259 is connected and restore the APIC settings back during kexec boot or kdump boot. This enables getting timer interrupts in new kernel in legacy mode.
This patch is needed to make kexec and kdump work on some systems, especially opteron boxes. Otherwise the second kernel does not receive timer interrupts during early boot hence hangs.
I understand, that you are inclined towards remembering all the APIC states and simply restore it back instead of putting hooks. This will work well for kexec but not for kdump because in kdump system can crash on non-boot cpu.
Restoring BIOS APIC state can make sure that BIOS designated boot cpu will always be able to see timer interrupts in legacy mode but same does not hold good if new kernel boots on some other cpu as is the case with kdump.
In case of kexec boot, we relocate to boot cpu but in case of kdump we don't because it was suggested that in some extreme cases of crash, boot cpu might not respond even to NMI and relocation to boot cpu will not be possible.
Can you please re-consider this patch for inclusion.
Thanks Vivek
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