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path: root/include/asm-sparc64/hvtramp.h
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2008-03-21[SPARC64]: Remove most limitations to kernel image size.David S. Miller
Currently kernel images are limited to 8MB in size, and this causes problems especially when enabling features that take up a lot of kernel image space such as lockdep. The code now will align the kernel image size up to 4MB and map that many locked TLB entries. So, the only practical limitation is the number of available locked TLB entries which is 16 on Cheetah and 64 on pre-Cheetah sparc64 cpus. Niagara cpus don't actually have hw locked TLB entry support. Rather, the hypervisor transparently provides support for "locked" TLB entries since it runs with physical addressing and does the initial TLB miss processing. Fully utilizing this change requires some help from SILO, a patch for which will be submitted to the maintainer. Essentially, SILO will only currently map up to 8MB for the kernel image and that needs to be increased. Note that neither this patch nor the SILO bits will help with network booting. The openfirmware code will only map up to a certain amount of kernel image during a network boot and there isn't much we can to about that other than to implemented a layered network booting facility. Solaris has this, and calls it "wanboot" and we may implement something similar at some point. Signed-off-by: David S. Miller <davem@davemloft.net>
2007-07-16[SPARC64]: Initial LDOM cpu hotplug support.David S. Miller
Only adding cpus is supports at the moment, removal will come next. When new cpus are configured, the machine description is updated. When we get the configure request we pass in a cpu mask of to-be-added cpus to the mdesc CPU node parser so it only fetches information for those cpus. That code also proceeds to update the SMT/multi-core scheduling bitmaps. cpu_up() does all the work and we return the status back over the DS channel. CPUs via dr-cpu need to be booted straight out of the hypervisor, and this requires: 1) A new trampoline mechanism. CPUs are booted straight out of the hypervisor with MMU disabled and running in physical addresses with no mappings installed in the TLB. The new hvtramp.S code sets up the critical cpu state, installs the locked TLB mappings for the kernel, and turns the MMU on. It then proceeds to follow the logic of the existing trampoline.S SMP cpu bringup code. 2) All calls into OBP have to be disallowed when domaining is enabled. Since cpus boot straight into the kernel from the hypervisor, OBP has no state about that cpu and therefore cannot handle being invoked on that cpu. Luckily it's only a handful of interfaces which can be called after the OBP device tree is obtained. For example, rebooting, halting, powering-off, and setting options node variables. CPU removal support will require some infrastructure changes here. Namely we'll have to process the requests via a true kernel thread instead of in a workqueue. workqueues run on a per-cpu thread, but when unconfiguring we might need to force the thread to execute on another cpu if the current cpu is the one being removed. Removal of a cpu also causes the kernel to destroy that cpu's workqueue running thread. Another issue on removal is that we may have interrupts still pointing to the cpu-to-be-removed. So new code will be needed to walk the active INO list and retarget those cpus as-needed. Signed-off-by: David S. Miller <davem@davemloft.net>