Vivek Goyal <[EMAIL PROTECTED]> writes: >> I guess at this point the easy case is that we modify /sbin/kexec to support >> it. And the other bootloaders can come be upgraded if the feature is >> interesting enough. >> >> > On i386, somebody already found an interesting usage of > CONFIG_PHYSICAL_START >> > where he was running his kernel above 16MB so that he can maximize on >> > DMA ZONE. Can't think of any usage for x86_64 at the moment but I think >> > down the line people might come up with such usages. >> >> Agreed. We do have CONFIG_PHYSICAL_ALIGN that can handle that case, >> although I admit that is a bit of a hack. >> > > Yes, but x86_64 will not have any of those options and only way to run > kernel will be either use kexec or modify your boot-loader to so that > it can handle relocatable images.
True. >> > To me, retaining CONFIG_PHYSICAL_START gives added flexibility to the user, >> > at the expense of reduced simplicity. We should definitely change the type >> > of vmlinux to ET_DYN but at the same time it might still be worth to retain >> > CONFIG_PHYSICAL_START option. >> >> I think something like CONFIG_PHYSICAL_START currently gives us very >> little gain, and is hard to use correctly, and there are alternative >> solutions. So if we can get rid of it, by only inconveniencing users >> who want load their kernels at a weird address it is worth it. >> >> >> I think I can switch the vmlinux header type in about 100 lines or so >> >> of code. Assuming I can ever get 30 minutes with the appropriate >> >> kernel. >> >> >> > >> > That would be awesome. Then vmlinux will be relocatable too. (Officially). >> >> Yes. For x86_64 I can do this. i386 is more difficult. (Although with >> a little cleverness we can move the code that processes relocations into >> vmlinux). >> > > Performing relocations in vmlinux will be interesting. That way i386 vmlinux > too will become relocatable and only piece of puzzle to solve will be to > make vmlinux of type ET_DYN. Actually making vmlinux have type ET_DYN is the easier piece. Basically the quick way to do this is to have an arch specific: "cmd_vmlinux__" like uml does so we can edit things after the make. Changing an integer in an ELF header is simple. Inserting the code to perform the relocations feels a bit trickier but we can probably just dump it in head.S like we do on x86_64. We still need to insert the actual relocations to process though. Which requires all of the post processing we currently do just called at a slightly different location. Eric - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
