Re: [PATCH] cdrom access patch

[Bean]

On Sat, Mar 15, 2008 at 4:49 PM, Vesa Jääskeläinen <address@hidden> wrote:
> Bean wrote:
>  > On Sat, Mar 15, 2008 at 4:58 AM, Vesa Jääskeläinen <address@hidden> wrote:
>  >> Bean wrote:
>  >>  > Hi,
>  >>  >
>  >>  > I have an idea, why not have both names, (hdN) and (cd), hopefully
>  >>  > this will make everyone happy.
>  >>  >
>  >>
>  >>  Hi Bean,
>  >>
>  >>  I think I suggested it already ;)
>  >>
>  >>  Device alias is ok for me :) (and use of cd[nro] is more favorable).
>  >
>  > Ok, the new patch add (cd0) alias for cdrom device, the corresponding
>  > (hdN) is also present.
>
>  I am just wondering that this implementation is limited to cd0, you
>  cannot have cd1.
>
>  Consider following scenario:
>  User boots with biosdisk enabled from bootable CD, gets bootdrive from
>  there assigns (cd0) for this device. User loads ata module to get access
>  to more removable disk drives (cd/dvd/bdr) and then system would assign
>  new device aliases like cd1, cd2 depending on how many device there is
>  in system.
>
>  This could be done by something like this:
>
>  in biosdisk:
>  if disk.drivetype == cd then
>    add_alias(ALIAS_TYPE_CD, disk)
>
>  in ata:
>  if disk.drivetype == cd then
>    add_alias(ALIAS_TYPE_CD, disk)
>
>  Idea of this is that if there are multiple CD's you get new aliases
>  identifier always incremented by one. With this you could even do following:
>
>  biosdisk:
>  disk.bios_device_nro = 0x0;
>  add_alias(ALIAS_TYPE_FLOPPY, disk) // disk becomes as alias (fd0)
>
>  disk.bios_device_nro = 0x80;
>  add_alias(ALIAS_TYPE_HDD, disk) // disk becomes as alias (hd0)
>
>  disk.bios_device_nro = 200;
>  add_alias(ALIAS_TYPE_CDROM, disk) // disk becomes as alias (cd0)
>
>  ata: // second ATA controller on system
>  disk.bios_device_nro = NOTSET; // -1 (?)
>  add_alias(ALIAS_TYPE_HDD, disk) // disk becomes as alias (hd1)
>
>  And then have a disk as a generic disk info block where there is
>  function pointers to in example biosdisk or ata modules to handle reading.
>
>  In case if user installs emulation layer for in example ATA hdd in this
>  scanario, then this bios_device_nro would be filled.
>
>  In here also biosdisk will be checked if it supports outputting of
>  physical device information using EDD, and if it does, then it can
>  filter out ata accesses for those device that bios already supports.
>
>  In this system there could be following standard names based on driver
>  for devices:
>
>  (pcbios0) // floppy
>  (pcbios128) // hdd
>  (pcbios200) // cd
>
>  (ata0)
>  (ata2)
>  (atapi1)
>  (atapi3)
>
>  Or even more deeper with physical chain of devices like:
>  (pciXXXX/ata0)
>  (pcbios/disk128)
>
>  Just something to think about :)

This is a great idea, in fact, we don't even need to call add_alias
explicitly. We can add a new field device_type in disk, when it's
TYPE_xxx, we create the alias automatically in grub_device_iterate.

-- 
Bean