Messages in this thread |  | | | Date | Mon, 10 Jan 2000 04:38:06 +0100 | | From | almesber@lrc ... | | Subject | Re: [Semi-OT] hot-swapping kernels |
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Matthias Andree wrote: > I think a kernel as second-stage bootloader is overkill.
Functionality-wise, yes. Maintenance-wise, probably not. Let me explain: the complexity of the boot process is gradually increasing over time. One source of complexity is added functionality in the Linux kernel, e.g. RAID. Another source of complexity are more complex setups people want to build, e.g. see the tftp thread in linux-kernel.
Mirroring major new kernel functionality in a boot loader tends to be a time-consuming business and always contains the risk of version drift. Also, if a feature is missing in the boot loader, it will be hard to add by users who need it.
On the other hand, a Linux kernel is implicitly capable of handling everything one might successfully throw at a Linux kernel. Somebody who is able to make use of a given feature in a "regular" system should also find it quite feasible to make use of it from the second stage. In particular, normally, no modification of the boot loader will be necessary.
Of course, using a little Linux system as a second stage loader may appear excessive. One issue can be space. On most regular PCs, there is sufficient storage space nowadays to afford this overhead. There will always be exceptions where space is highly critical (e.g. embedded, diskless, etc.) so the current, more streamlined boot process needs to continue to work.
Another issue can be time. That's why I think it will be necessary that the first kernel can pass the results of bus scans etc. directly to the second kernel. The latter can then skip this process, or possibly initiate a new scan in the background (e.g. if the second kernel may be able to see more devices), while already proceeding with the information passed from the other kernel.
> I think people should rather work merging the advantages of LILO and > those of GRUB, to get a DECENT bootloader.
Don't forget all the non-i386 architectures. Also, there are several specialized boot loaders on i386 alone (e.g. SYSLINUX), which may have to track some changes too.
- Werner
-- _________________________________________________________________________ / Werner Almesberger, ICA, EPFL, CH werner.almesberger@ica.epfl.ch / /_IN_N_032__Tel_+41_21_693_6621__Fax_+41_21_693_6610_____________________/ - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.rutgers.edu Please read the FAQ at http://www.tux.org/lkml/
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