- writing to a PTY master side blocks if there is not already a
blocked reader on the slave side, and select now reflects this;
- internally, TTY now uses a test based on "caller != NONE" rather
than "grant != GRANT_INVALID" to identify whether a call is
currently ongoing;
- "offset" fields have been removed as they equal the corresponding
"cum" fields;
- improved variable typing and function naming here and there;
- various other small fixes.
Change-Id: I6b51452888942e864b4e034e8c8490576184a23e
Opening and closing the master side of a pseudo terminal without
opening the slave side would result in the pseudo terminal becoming
permanently unavailable. In addition, reopening the slave side
would be possible but not allow for I/O. Finally, attempting to
open an in-use master would wipe its I/O state. These issues have
been resolved.
Change-Id: I9235e3d9aba321803f9280b86b6b5e3646ad5ef3
- change all sync char drivers into async drivers;
- retire support for the sync protocol in libchardev;
- remove async dev style, as this is now the default;
- remove dev_status from VFS;
- clean up now-unused protocol messages.
Change-Id: I6aacff712292f6b29f2ccd51bc1e7d7003723e87
The async char protocol already has this, so this patch closes the
gap between the two protocols a bit. Support for this flag has been
added to all sync char drivers that support CANCEL at all.
The LOG driver was already using the asynchronous protocol, but it
did not support the nonblocking transfer flag. This has been fixed
as well.
Change-Id: Ia55432c9f102765b59ad3feb45a8bd47a782c93f
.Split TTY in order to support both x86 and ARM.
.Add support for the TI 16750 UARTs on OMAP35x.
.Various other improvements:
.Kernel messages are printed using generic terminal write
functions. That is, they are no longer directly displayed
on the console.
.The console can now be displayed on any terminal. This
is configured by the "console={tty00,tty01,ttyc2,ttyc3,ttyc4}"
boot variable -- basically any valid /dev/tty* terminal.
.Cutify kernel messages with colors. Configured by
"kernelclr={1,2,3,4,5,6,7}" boot variable.
. all invocations were S or D, so can safely be dropped
to prepare for the segmentless world
. still assign D to the SCP_SEG field in the message
to make previous kernels usable
TTY has no way of keeping track of multiple readers for a tty minor
device. Instead, it stores a read request for the last reader only.
Consequently, the first ("overwritten") reader gets stuck on a read
request that's never going to be finished. Also, the overwriting
causes a grant mismatch in VFS when TTY returns a reply for the
second reader.
This patch is a work around for the actual problem (i.e., keeping track
of multiple readers). It checks whether there is a read operation in
progress and returns an error if it is --preventing that reader from
getting overwritten and stuck. It fixes a bug triggered by executing
'top | more' and pressing the space bar for a while (easily reproducable
in a VM, not on hardware).
This patch separates the character and block driver communication
protocols. The old character protocol remains the same, but a new
block protocol is introduced. The libdriver library is replaced by
two new libraries: libchardriver and libblockdriver. Their exposed
API, and drivers that use them, have been updated accordingly.
Together, libbdev and libblockdriver now completely abstract away
the message format used by the block protocol. As the memory driver
is both a character and a block device driver, it now implements its
own message loop.
The most important semantic change made to the block protocol is that
it is no longer possible to return both partial results and an error
for a single transfer. This simplifies the interaction between the
caller and the driver, as the I/O vector no longer needs to be copied
back. Also, drivers are now no longer supposed to decide based on the
layout of the I/O vector when a transfer should be cut short. Put
simply, transfers are now supposed to either succeed completely, or
result in an error.
After this patch, the state of the various pieces is as follows:
- block protocol: stable
- libbdev API: stable for synchronous communication
- libblockdriver API: needs slight revision (the drvlib/partition API
in particular; the threading API will also change shortly)
- character protocol: needs cleanup
- libchardriver API: needs cleanup accordingly
- driver restarts: largely unsupported until endpoint changes are
reintroduced
As a side effect, this patch eliminates several bugs, hacks, and gcc
-Wall and -W warnings all over the place. It probably introduces a
few new ones, too.
Update warning: this patch changes the protocol between MFS and disk
drivers, so in order to use old/new images, the MFS from the ramdisk
must be used to mount all file systems.
Before safecopies, the IO_ENDPT and DL_ENDPT message fields were needed
to know which actual process to copy data from/to, as that process may
not always be the caller. Now that we have full safecopy support, these
fields have become useless for that purpose: the owner of the grant is
*always* the caller. Allowing the caller to supply another endpoint is
in fact dangerous, because the callee may then end up using a grant
from a third party. One could call this a variant of the confused
deputy problem.
From now on, safecopy calls should always use the caller's endpoint as
grant owner. This fully obsoletes the DL_ENDPT field in the
inet/ethernet protocol. IO_ENDPT has other uses besides identifying the
grant owner though. This patch renames IO_ENDPT to USER_ENDPT, not only
because that is a more fitting name (it should never be used for I/O
after all), but also in order to intentionally break any old system
source code outside the base system. If this patch breaks your code,
fixing it is fairly simple:
- DL_ENDPT should be replaced with m_source;
- IO_ENDPT should be replaced with m_source when used for safecopies;
- IO_ENDPT should be replaced with USER_ENDPT for any other use, e.g.
when setting REP_ENDPT, matching requests in CANCEL calls, getting
DEV_SELECT flags, and retrieving of the real user process's endpoint
in DEV_OPEN.
The changes in this patch are binary backward compatible.
include grant id in DEV_REVIVE messages.
. Removal of TTY_FLAGS field (and so O_NONBLOCK support).
. Fixed CANCEL behaviour and return code on blocking I/O,
previously handled by O_NONBLOCK
. Totally removed REVIVE replies, previously still possible on
blocking ioctls (REVIVE directly called) and ptys (missing TTY_REVIVE
check), removes deadlock bug with FS
. Removed obsolete *COMPAT options and associated code
