On Wed, 10 Nov 2021 17:30:54 +0000, Matthew Wilcox wrote: > On Wed, Nov 10, 2021 at 01:38:48PM +0100, David Disseldorp wrote: > > Contrary to the buffer-format.rst documentation, initramfs cpio > > extraction does not support "crc" archives, which carry "070702" > > header magic. Make it a little clearer that "newc" (magic="070701") is > > the only supported cpio format, by extending the POSIX.1 ASCII > > (magic="070707") specific error message to also cover "crc" magic. > > Wouldn't it be easier to just add support? Well, no, this patch already exists. :-) > As far as I can tell from > looking at documentation, the "crc" format is the same as newc, except > that it uses some reserved bits to store the crc. Since we ignore those > bits, we could just check for either 070701 or 070702. Sure, it'd be pretty straightforward to implement "crc" format support, but I'm not sure how useful a 32-bit checksum would be... If we're going down this route, wouldn't proper IMA/EVM support make sense via some new cpio variant with space for the attributes (or as header/trailer like bootconfig)? cc'ing Jeff, as I seem to recall him mentioning some work in this area. Cheers, David
