Ok. Forget my last message. 2 KB was the actual dimension of the file, ls shows that on my filesystem the file correctly takes 4 KB.
Back to topic, as far as I understand, there's no way to chainload isolinux bootloader from grub. Some days ago I tried the procedure through loopback device, with the same result. I think the created loop device is not exactly an iso filesystem, right? Thanks for your time and for the explanations.. 2016-02-03 16:12 GMT+01:00 4javier <[email protected]>: > In effect I have the El Torito boot catalog in the same directory, and its > size is 2KB. But If I open it with an hex editor, it has just early byte > wrote, and about 90% of the rest is just filled with zeros. I think it's > due to blocksize. But I can't understand how it could be just 2KB when > blocksize of the partition is 4096. Shouldn't it be 4 KB? > > 2016-02-03 15:39 GMT+01:00 Andrei Borzenkov <[email protected]>: > >> On Wed, Feb 3, 2016 at 5:29 PM, 4javier <[email protected]> wrote: >> > You're right. My fault thinking that "chainloader" command would have >> ran >> > directly the chained bootloader with no need of "boot" command. Anyway, >> I >> > just tried, and shell just shows a blinking cursor on a new line, doing >> > nothing. >> > >> >> Well ... chainloader command loads single sector. El Torito boot image >> can be of arbitrary (withing some limits) length. As soon as >> isolinux.bin exceeds 512 bytes, it's going to fail. >> >> Second problem is whether isolinux.bin was built for specific memory >> address and for which one (this information is present in El Torito >> boot catalog and is missing here of course). >> >> Third consideration is, block size on CD is 2048 bytes which does not >> match what you have on HDD (either 512 or 4096). It will likely make >> it impossible for isolinux.bin to read anything. >> >> > >> > 2016-02-03 14:51 GMT+01:00 Andrei Borzenkov <[email protected]>: >> >> >> >> On Wed, Feb 3, 2016 at 3:20 PM, 4javier <[email protected]> wrote: >> >> > chainloader /isolinux/isolinux.bin >> >> > >> >> > I always get Error: Invalid Signature. >> >> > If I try to force chainloading, it just get back to the prompt. >> >> > >> >> >> >> Every loader command in grub just "get back to prompt". You need to >> >> use "boot" command to actually jump to loaded code (but I doubt it >> >> will work). >> > >> > >> > >
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