muta...@gmail.com wrote:
> What is the reason that drivers for various bits of
> hardware are being put into the operating system,
> usually only the very latest version of Windows,
> instead of being flashed onto the firmware with
> an API that is available (via BIOS or UEFI) to all
> operating systems?
There is simple answer: drivers are really part of operating
system. In more details: driver interface, that is way
in which drivers interact with operating system is
important part of design of operating system. DOS
took CPM design with BIOS interface. This design was
good for small machines but severly limited possible
DOS improvements.
As simple example of possible troubles look at interrupt:
driver that blocks interrupts and returns control to
operating system only when it finishded is easy to
write, but will have low performance on anything reasonably
new. And single such driver may exclude using better
drivers for other devices (because such drivers need
to react timely to interrupts). There is question of
memory needed by drivers: on classic PC high performace
floppy driver needs track buffer which must be allocated
withing single 64kB memory block (to satisfy DMA restrictions).
Allocating such block at system startup is easy. But if
machine is 32kB PC, then track buffer is likely to be
considered too much overhead.
Another trouble is USB: logically there is single bus
with several devices which need to be polled. Bus
controller performs rather complex operations affection
all devices. Drivers for devices on USB bus must
cooperate with bus control, no single device should
take exclusive control of the bus. Since there are
limited number of bus controller chips, it is natural
to put bus control in operating system and drivers
for specific devices operate via operating system
calls. But then clearly drivers are specific to
operating system...
--
Waldek Hebisch
--- SoupGate-Win32 v1.05
* Origin: you cannot sedate... all the things you hate (1:229/2)
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