On Tue 18 Apr 2017 at 20:32:38 +0200, Pascal Hambourg wrote: > Le 17/04/2017 à 21:05, Brian a écrit : > >On Mon 17 Apr 2017 at 08:48:50 +0000, Curt wrote: > > > >>On 2017-04-17, David Wright <deb...@lionunicorn.co.uk> wrote: > >>> > >>>Oddly, this ancient laptop (Acer) has a slot that makes the SD card > >>>look like a /dev/sdX disk, and the BIOS is happy to boot from it. > >> > >>I have an Acer X1430 with an internal "Multi-in-1 Media Card Reader" for > >>which an SD card inserted into the reader is recognized by the kernel as > >>as a /dev/sdX disk. > > > >You have to be careful here to distinguish between what the OS can > >recognise and what GRUB can see. The kernel will be using the Multimedia > >Card device drivers to detect the device > > Not always. If the card reader identifies itself as a generic USB mass > storage device, then the kernel will use the same drivers as for USB drives > and assign the same kind of name /dev/sd*. It seems that in this case, most > BIOS recognize it and can boot from it. > > I guess that the kernel will use MMC device drivers only if the card reader > identifies itself as a native SD/MMC card reader.
Seems reasonable and sensible. However, my main point was that the kernel identifying a card as a /dev/sdX disk does not imply it will necessarily be visible to GRUB and bootable by it. -- Brian.
