I submit this for what it is worth. Probably not a lot.
I had noticed in the past that it seemed the 486 kernel was larger than the
386 kernel. So when I set up to compile the 2.2.19 kernel I decided to set
up a script file to compile the kernel in all five CPU flavors and also the
386 with FPU support. For completeness I also recorded the kernel sizes when
compressed with upx. The small config file used for the small kernel is a
stripped down one with very limited functionality. The large config file is
based on Ewald Wasscher's "Huge" config file. I have most of the LEAF patches
applied to the kernel source.
bzImage bzImage upx upx diff diff
small large small large small large
386 408314 512292 353527 445007 54787 67285
486 415759 520760 360951 454031 54808 66729
586 405505 508817 351555 442535 53950 66282
PENT 405438 508729 351403 442451 54035 66278
PRO 405437 508729 351403 442455 54034 66274
386+FPU 436303 539876 377079 472067 59224 67809
The first column is of course the CPU flavor. The second and third columns
are the bzImage sizes. The fourth and fifth columns are the bzImages
compressed with upx. Finally the sixth and seventh columns are the size
differences between the bzImages and the upx images. Kernel compression
varied between 12.5% and 13.5% with a size difference from 54K to 67K.
bzImage bzImage upx upx
small large small large
386 2877 3563 2124 2556
486 10322 12031 9548 11580
586 68 88 152 84
PENT 1 0 0 0
PRO 0 0 0 4
386+FPU 30866 31147 25676 29616
In this table each entry shows haw much larger the kernel is than the
smallest kernel in that column. There is little difference in the sizes of
the 586, Pentium and Pentium Pro kernels. The 486 kernel is significantly
larger than the 386 kernel, ranging from 7424 bytes to 9024 bytes larger.
And finally there is the 386+FPU kernel. Not much to be said about it other
than don't use it unless you need to. :)
It looks to me that there is no compelling reason to compile kernels other
than the "generic" 586 kernel, the 386 kernel and the 386FPU kernel. IIRC
there is only a 2%-3% difference in speed between different kernel versions.
Not enough to worry about.
Upx'd kernels is another issue. The disk savings is significant. And I don't
recall anybody mentioning they had problems with a upx'd kernel. Should they
become the "standard" kernel for LEAF? That extra 50K or 60K of room sure is
tempting...
