Re: [grub] Experiencing difficulties to access USB key files

[Andrei Borzenkov]

25.01.2016 11:20, Arbiel (gmx) пишет:
>>> Do you mean that "hd0,msdos1" and so on, are sort of symbols for
>>> information understood by the BIOS that grub own drivers do not understand ?
>> hd0 refers to disk accessible via BIOS. USB mass storage accessible
>> directly using USB drivers would be name usb0 (or whatever running
>> number). Command "nativedisk" attempts to find and replace new device
>> names in $root and $prefix.
> That's true. However, it does not translate $config_directory, and I
> haven't found any way to translate it, but to set it to $prefix. And
> this is only acceptable for the configuration file pointed by core.
> 
> Using "nativedisk", grub failed and went down to grub rescue when placed
> as the first command of grub.cfg. I had to delay it until after the
> first disk access. And then I got thrice " hd0, msdos1 disk not found",
> but grub stayed alive.

nativedisk is more or less debugging tool. There can be any number of
custom variables holding device references in unexpected places.

If you insist on using it in configuration script, you can use e.g.
probe+regexp+search (which is effectively what nativedisk does anyway):

regexp --set 1:device --set 2:path '^\(([^)]*)\)(.*)$' "$config_directory"
probe --set uuid $device
nativedisk
search --set device --fs-uuid $uuid
set config_directory="($device)$path"

> I have also seen that after the command, prefix was set to
> (device)//path, instead of (device)/path. Is grub reducing multiple
> occurences of "/" in a file path to a single one ?

Yes. Like Unix too.

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