On 2024-02-16 at 14:44, Albretch Mueller wrote: > I've got a relatively old laptop with an ATI Radeon HD card, which > firmware I can't update. Wild pixelations happen even on relatively > simple pages not just videos. It seems to be a common problem. What I > have searched and found out is that I will have to un/repack initramfs > ..., but I haven't found a relatively safe, complete procedure. > > How can you update the initramfs on read-only media? At a guess: * Copy the read-only media to a writable location. This is "the image tree". * Extract the initramfs from the file which contains it, into an empty directory. This is "the extracted initramfs". * Modify the files in the extracted initramfs. The result is "the updated extracted initramfs". * Create a new initramfs whose contents are the updated extracted initramfs. Copy it into the image tree. The result is "the updated image tree". * Write the updated image tree to new read-only media. Depending on what form the media is, this may require other steps first; for example, if it's a CD or DVD, you will probably need to create an ISO using a tool like genisoimage or (I think) xorriso. Read-only media is by definition not update-able. You can only create new media, using a modified copy of the files from the read-only media. I have successfully built updated versions of live-boot CDs, with updated kernels and initrd environments and so forth, using this basic method. It has been a long time, but I can confirm that it works, if done correctly. Now, if what you want to know is how to extract the initramfs... that depends on how it's compressed, which may depend on what live-system boot media you're working with, but typically it will be a gzip-compressed cpio archive. In that case, working from memory based on the last time I was doing such a thing, what you'd need to do is something like: $ mkdir /tmp/extract $ cp /path/to/image/tree/initrd.gz /tmp/extract $ gunzip /tmp/extract/initrd.gz $ mkdir /tmp/extract/extracted-initramfs $ cd /tmp/extract/extracted-initramfs $ cpio -i < ../initrd And to create a new one (without overwriting anything created during the above), you'd do something like: $ mv /tmp/extract/initrd /tmp/extract/initrd.unmodified $ cd /tmp/extract/extracted-initramfs $ find . | cpio -o > ../initrd $ gzip -9 /tmp/extract/initrd $ mv /tmp/extract/initrd.gz /path/to/image/tree/initrd.gz *DO* *NOT* just take this as a recipe to follow. Read the documentation of the programs involved, look for examples online if that documentation doesn't make things clear in your mind, and use this as a *starting point* to figure out what the correct thing to do in your circumstance actually is. -- The Wanderer The reasonable man adapts himself to the world; the unreasonable one persists in trying to adapt the world to himself. Therefore all progress depends on the unreasonable man. -- George Bernard Shaw
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