constrained to a small number of sessions by the small on-card memories found
in newer devices. This is really a stopgap solution as having session state
in main memory incurs a (small but noticeable) performance penalty. The better
solution is to manage session state so that it's cached on chip.
Obtained from: openbsd
The changes in the next commit would make the code totally unreadable
if the #ifdef'ing were maintained.
It might make a lot of sense to split if_cx.c in a netgraph related
and in a tty related file but I will not attempt that without hardware.
handle DMA addresses located above 1GB. The LBA(loop begin address)
register which holds DMA base address is 32bits register. But the
MSB 2bits are used for other purposes. This effectivly limits the
DMA address space up to 1GB.
Approved by: jake (mentor)
Reviewed by: truckman, matk
assign DMA address to the wrong address. It can cause system lockup
or other mysterious errors. Since most sound cards requires low DMA
address(BUS_SPACE_MAXADDR_24BIT) sndbuf_alloc() would fail when the
audio driver is loaded after long running of operations.
Approved by: jake (mentor)
Reviewed by: truckman, matk
- Implement dcons_ischar() and dcons_load_buffer().
- If loader passed a dcons buffer address, keep using it.
(We still need a patch to cheat memory management system.)
asynchronous. I realize that this means the custom application will
not work as written, but it is not okay to break most users of ugen(4).
The major problem is that a bulk read transfer is not an interrupt
saying that X bytes are available -- it is a request to be able to
receive up to X bytes, with T timeout, and S short-transfer-okayness.
The timeout is a software mechanism that ugen(4) provides and cannot
be implemented using asynchronous reads -- the timeout must start at
the time a read is done.
The status of up to how many bytes can be received in this transfer
and whether a short transfer returns data or error is also encoded
at least in ohci(4)'s requests to the controller. Trying to detect
the "maximum width" results in using a single buffer of far too
small when an application requests a large read.
Even if you combat this by replacing all buffers again with the
maximal sized read buffer (1kb) that ugen(4) would allow you to
use before, you don't get the right semantics -- you have to
throw data away or make all the timeouts invalid or make the
short-transfer settings invalid.
There is no way to do this right without extending the ugen(4) API
much further -- it breaks the USB camera interfaces used because
they need a chain of many maximal-width transfers, for example, and
it makes cross-platform support for all the BSDs gratuitously hard.
Instead of trying to do select(2) on a bulk read pipe -- which has
neither the information on desired transfer length nor ability to
implement timeout -- an application can simply use a kernel thread
and pipe to turn that endpoint into something poll-able.
It is unfortunate that bulk endpoints cannot provide the same semantics
that interrupt and isochronous endpoints can, but it is possible to just
use ioctl(USB_GET_ENDPOINT_DESC) to find out when different semantics
must be used without preventing the normal users of the ugen(4) device
from working.
New devicename is ttyy{unit}{port}
No callout devices created as there is no modemcontrol on these ports.
Add data structure to represent each port to avoid excessive array use.
from within umass_ufi_transform(). This includes the 12-byte commands
FORMAT_UNIT, WRITE_AND_VERIFY, VERIFY, and READ_FORMAT_CAPACITIES
(sorted in numerical order).
Reviewed by: ken, scottl
MFC after: 2 weeks
md(8). The former is generally not going to fail, but the latter can
fail when the underlying swap device returns an error.
There are still plenty of other places where vm_pager_get_pages() failing
will lead directly to crashes, so it's a good idea to put your swap on
RAID if you care enough to put any of your disks on RAID....
that conjures up the device node so it isn't true PNP. Noticed by jhb@.
* Add an attachment for esscontrol since it too uses ISA_PNP_PROBE.
* Move an attachment from snd_mss to snd_pnpmss. The latter is the real
PNP user.
* Fix a bug where caches were flushed on non-C3 transitions.
* Be sure a working flush cache instruction is present before using it.
* Disable C3 completely if it isn't present.
may want to shut down here but the chance of BIOS vendors getting this
wrong is high. They're only supposed to announce this when all batteries
hit their critical level but past experience indicates we should be
conservative about this for now.
- Trade off granularity to reduce overhead, since the current model
doesn't appear to reduce contention substantially: move to a single
harvest mutex protecting harvesting queues, rather than one mutex
per source plus a mutex for the free list.
- Reduce mutex operations in a harvesting event to 2 from 4, and
maintain lockless read to avoid mutex operations if the queue is
full.
- When reaping harvested entries from the queue, move all entries from
the queue at once, and when done with them, insert them all into a
thread-local queue for processing; then insert them all into the
empty fifo at once. This reduces O(4n) mutex operations to O(2)
mutex operations per wakeup.
In the future, we may want to look at re-introducing granularity,
although perhaps at the granularity of the source rather than the
source class; both the new and old strategies would cause contention
between different instances of the same source (i.e., multiple
network interfaces).
Reviewed by: markm
