# Kernel config -- Zlib support?

## Sivar

I notice that in the Library Routines section of the kernel config (menuconfig) that one can choose Zlib compression/decompression support. Will this allow the system to use kernel level zlib routines whenever a person runs gzip, or is it just for HTTP compression, or what?

Additionally, zlib decompression appears like three or four times in the kernel source. Will this add it yet again or use one of the existing copies? (there is no help yet, it seems to be a brand new option)

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## syadnom

i wont lie to you, im not SURE, but i think this just allows the kernel to compress the libraries to make it smaller, i dont think it has anything to do with using gzip...

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## delta407

Looking at /usr/src/linux/lib/config.in:

```
if [ "$CONFIG_CRAMFS" = "y" -o \

     "$CONFIG_PPP_DEFLATE" = "y" -o \

     "$CONFIG_JFFS2_FS" = "y" -o \

     "$CONFIG_ZISOFS_FS" = "y" ]; then

   define_tristate CONFIG_ZLIB_INFLATE y

...

if [ "$CONFIG_PPP_DEFLATE" = "y" -o \

     "$CONFIG_JFFS2_FS" = "y" ]; then

   define_tristate CONFIG_ZLIB_DEFLATE y
```

It seems that decompression is included automatically if you use CramFS, PPP deflate, JFFS2, or the compressed CD-ROM extensions. Compressions in included automatically only with PPP deflate and JFFS2.

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