On Mon, Sep 07, 2015 at 09:10:03PM +0200, Maxime de Roucy wrote: > Le lundi 07 septembre 2015 à 10:36 -0400, Kevin O'Connor a écrit : > > I don't understand what Maxime is reporting (via the documentation > > patch), nor what Matt's patch above fixes. Could someone provide a > > description of the problem/feature? > > Lets say you have one SATA drive and one USB drive connected to your > board. > The SATA drive is blank (no data on it). > The USB drive contain a bootable operating system. > > You configure the bootorder to : > SATA > USB > PXE > HALT > > In this situation the user imagine SeaBIOS boot to USB as it will fail > to boot from SATA… that's not the case.
This is a quirk of the BIOS/bootloader interface - bootloaders on "hard drives" are only able to boot from the C: drive (technically, the drive mapped to 0x80). SeaBIOS can only map one drive as C: per boot - so in the above example, if SeaBIOS maps the SATA drive as C: then only the SATA "hard drive" is bootable. I don't see this as a huge issue though, because the user can simply reboot and select the USB drive from the boot menu. > SATA and USB are both treat as IPL_TYPE_HARDDISK and when SeaBIOS list > the devices it only keep the highest priority device of each type. > > SATA and USB are both present and SATA has a higher priority than USB. > PXE is another type (I don't know which one). > > So SeaBIOS only keep SATA and PXE. When it fail to boot from SATA as > the drive is blank it fallback to PXE instead of USB as the user > expected. I understand what you mean now. Not sure the best way to document it. > The Matt patch (as I understand it) add an USB type. SeaBIOS will still > only keep the highest priority device of each type but as SATA and USB > belongs to different type they will be kept. SeaBIOS will boot from USB > when it fail to boot from SATA. Matt's patch doesn't implement that. The patch would just attempt to boot from C: twice - which would just cause back-to-back failures if the C: drive is not bootable. -Kevin _______________________________________________ SeaBIOS mailing list [email protected] http://www.seabios.org/mailman/listinfo/seabios
