As of today we check SLC status before each call of __slc_rgn_op()
or __slc_entire_op(). So move status check into __slc_rgn_op()
and __slc_entire_op().
As we need to check status before *each* function execution and we
call slc_entire_op() and slc_rgn_op() from different places we add
this check directly into SLC entire/line functions instead of
their callers to avoid code duplication.
Signed-off-by: Eugeniy Paltsev <Eugeniy.Paltsev@synopsys.com>
Signed-off-by: Alexey Brodkin <abrodkin@synopsys.com>
Use is_isa_arcv2() function where it is possible instead of
CONFIG_ISA_ARCV2 define check to make code cleaner at the same time
keeping pretty much the same functionality - code in branches
under "if (is_isa_arcv2())" won't be compiled if CONFIG_ISA_ARCV2
is not defined, still we need a couple of CONFIG_ISA_ARCV2
ifdefs to make compiler happy. That's because code in
!is_isa_x() branch gets compiled and only then gets optimized
away.
Signed-off-by: Eugeniy Paltsev <Eugeniy.Paltsev@synopsys.com>
Signed-off-by: Alexey Brodkin <abrodkin@synopsys.com>
As we are planning to get rid of dozens of ifdef's in cache.c we
would better check D$ status before each entire/line operation
then check CONFIG_SYS_DCACHE_OFF config option.
This makes the code cleaner as well as D$ entire/line functions
remain functional even if we enable or disable D$ in run-time.
As we need to check status before *each* function execution and we
call D$ entire/line functions from different places we add
this check directly into D$ entire/line functions instead of
their callers to avoid code duplication.
Signed-off-by: Eugeniy Paltsev <Eugeniy.Paltsev@synopsys.com>
Signed-off-by: Alexey Brodkin <abrodkin@synopsys.com>
We're starting to use more and more BCRs and having their
definitions in-lined in sources becomes a bit annoying
so we move it all to a separate header.
Signed-off-by: Eugeniy Paltsev <Eugeniy.Paltsev@synopsys.com>
Signed-off-by: Alexey Brodkin <abrodkin@synopsys.com>
Move IOC initialization from cache_init() to a separate function.
This is the preparation for the next patch where we'll switch
to is_isa_arcv2() function usage instead of "CONFIG_ISA_ARCV2"
ifdef.
Also it makes cache_init function a bit cleaner.
Signed-off-by: Eugeniy Paltsev <Eugeniy.Paltsev@synopsys.com>
Signed-off-by: Alexey Brodkin <abrodkin@synopsys.com>
We don't implement separate flush_dcache_all() intentionally as
entire data cache invalidation is dangerous operation even if we flush
data cache right before invalidation.
There is the real example:
We may get stuck in the following code if we store any context (like
BLINK register) on stack in invalidate_dcache_all() function.
BLINK register is the register where return address is automatically saved
when we do function call with instructions like 'bl'.
void flush_dcache_all() {
__dc_entire_op(OP_FLUSH);
// Other code //
}
void invalidate_dcache_all() {
__dc_entire_op(OP_INV);
// Other code //
}
void foo(void) {
flush_dcache_all();
invalidate_dcache_all();
}
Now let's see what really happens during that code execution:
foo()
|->> call flush_dcache_all
[return address is saved to BLINK register]
[push BLINK] (save to stack) ![point 1]
|->> call __dc_entire_op(OP_FLUSH)
[return address is saved to BLINK register]
[flush L1 D$]
return [jump to BLINK]
<<------
[other flush_dcache_all code]
[pop BLINK] (get from stack)
return [jump to BLINK]
<<------
|->> call invalidate_dcache_all
[return address is saved to BLINK register]
[push BLINK] (save to stack) ![point 2]
|->> call __dc_entire_op(OP_FLUSH)
[return address is saved to BLINK register]
[invalidate L1 D$] ![point 3]
// Oops!!!
// We lose return address from invalidate_dcache_all function:
// we save it to stack and invalidate L1 D$ after that!
return [jump to BLINK]
<<------
[other invalidate_dcache_all code]
[pop BLINK] (get from stack)
// we don't have this data in L1 dcache as we invalidated it in [point 3]
// so we get it from next memory level (for example DDR memory)
// but in the memory we have value which we save in [point 1], which
// is return address from flush_dcache_all function (instead of
// address from current invalidate_dcache_all function which we
// saved in [point 2] !)
return [jump to BLINK]
<<------
// As BLINK points to invalidate_dcache_all, we call it again and
// loop forever.
Fortunately we may do flush and invalidation of D$ with a single one
instruction which automatically mitigates a situation described above.
And because invalidate_dcache_all() isn't used in common U-Boot code we
implement "flush and invalidate dcache all" instead.
Signed-off-by: Eugeniy Paltsev <Eugeniy.Paltsev@synopsys.com>
Signed-off-by: Alexey Brodkin <abrodkin@synopsys.com>
As of today __dc_line_op() and __dc_entire_op() support
only separate flush (OP_FLUSH) and invalidate (OP_INV) operations.
Add support of combined flush and invalidate (OP_FLUSH_N_INV)
operation which we planing to use in subsequent patches.
Signed-off-by: Eugeniy Paltsev <Eugeniy.Paltsev@synopsys.com>
Signed-off-by: Alexey Brodkin <abrodkin@synopsys.com>
__cache_line_loop() function was copied from Linux kernel
where per-line instruction cache operations are really used.
In U-Boot we use only entire I$ ops, so we can drop support of
per-line I$ ops from __cache_line_loop() because __cache_line_loop()
is never called with OP_INV_IC parameter.
Signed-off-by: Eugeniy Paltsev <Eugeniy.Paltsev@synopsys.com>
Signed-off-by: Alexey Brodkin <abrodkin@synopsys.com>
Move instruction cache entire operation to a separate function
because we are planing to use it in other places like
sync_icache_dcache_all().
Signed-off-by: Eugeniy Paltsev <Eugeniy.Paltsev@synopsys.com>
Signed-off-by: Alexey Brodkin <abrodkin@synopsys.com>
Disabling relocation might be useful on ARC for 2 reasons:
a) For advanced debugging with Synopsys proprietary MetaWare debugger
which is capable of accessing much more specific hardware resources
compared to gdb. For example it may show contents of L1 and L2 caches,
internal states of some hardware blocks etc.
But on the downside MetaWare debugger still cannot work with PIE.
Even though that limitation could be work-arounded with change of ELF's
header and stripping down all debug info but with it we won't have
debug info for source-level debugging which is quite inconvenient.
b) Some platforms which might benefit from usage of U-Boot basically
don't have enough RAM to accommodate relocation of U-Boot so we
keep code in flash and use as much of RAM as possible for more
interesting things.
Signed-off-by: Alexey Brodkin <abrodkin@synopsys.com>
Cc: Simon Glass <sjg@chromium.org>
Cc: Bin Meng <bmeng.cn@gmail.com>
Cc: Heiko Schocher <hs@denx.de>
Cc: York Sun <york.sun@nxp.com>
Cc: Stefan Roese <sr@denx.de>
This commit basically reverts two commits:
1. cf628f772e ("arc: arcv1: Disable master/slave check")
2. 6cba327bd9 ("arcv2: Halt non-master cores")
With mentioned commits in-place we experience more trouble than
benefits. In case of SMP Linux kernel this is really required as
we have all the cores running from the very beginning and then we
need to allow master core to do some preparatory work while slaves
are not getting in the way.
In case of U-Boot we:
a) Don't really run more than 1 core in parallel
b) We may use whatever core for that
Signed-off-by: Alexey Brodkin <abrodkin@synopsys.com>
U-Boot is a bit special piese of software because it is being
only executed once on power-on as compared to operating system
for example. That's why we don't care much about performance
optimizations instead we're more concerned about size. And up-to-date
compilers might produce much smaller code compared to
performance-optimized routines copy-pasted from the Linux kernel.
Here's an example:
------------------------------->8--------------------------
--- size_asm_strings.txt
+++ size_c_strings.txt
@@ -1,2 +1,2 @@
text data bss dec hex filename
- 121260 3784 3308 128352 1f560 u-boot
+ 120448 3784 3308 127540 1f234 u-boot
------------------------------->8--------------------------
See we were able to shave off ~800 bytes of .text section.
Also usage of string routines implemented in C gives us an ability
to support more HW flavors for free: generated instructions will match
our target as long as correct compiler option is used.
Signed-off-by: Alexey Brodkin <abrodkin@synopsys.com>
Only ARM and in some configs MIPS really implement arch_fixup_fdt().
Others just use the same boilerplate which is not good by itself,
but what's worse if we try to build with disabled CONFIG_CMD_BOOTM
and enabled CONFIG_OF_LIBFDT we'll hit an unknown symbol which was
apparently implemented in arch/xxx/lib/bootm.c.
Now with weak arch_fixup_fdt() right in image-fdt.c where it is
used we get both items highlighted above fixed.
Signed-off-by: Alexey Brodkin <abrodkin@synopsys.com>
Cc: Daniel Schwierzeck <daniel.schwierzeck@gmail.com>
Cc: Simon Glass <sjg@chromium.org>
Cc: York Sun <york.sun@nxp.com>
Cc: Stefan Roese <sr@denx.de>
Reviewed-by: Tom Rini <trini@konsulko.com>
Reviewed-by: Daniel Schwierzeck <daniel.schwierzeck@gmail.com>
This is useful to make sure no stale data exists in caches after bootloaders.
The worst thing could be some lines of cache were locked in a bootloader
for example during DDR recalibration and never unlocked. This may lead
to really unpredictable issues later down the line.
Signed-off-by: Eugeniy Paltsev <Eugeniy.Paltsev@synopsys.com>
Signed-off-by: Alexey Brodkin <abrodkin@synopsys.com>
We'd like to keep IOC HW at the same state as t is right after reset when we
start Linux kernel so there will be no re-configuration of IOC on the go.
The point is U-Boot doesn't benefit a lot from IOC as it doesn't do a
lot of DMA operations especially on multiple cores simultaneously.
At the same time re-configuration of IOC in run-time might become quite
a tricky experience because we need to make sure there're no DMA
trannsactions in flight otherwise unexpected consequencses might affect
us much later and debugging those kinds of issues will be a real
nightmare.
That said let's make our life easier a little bit.
Signed-off-by: Eugeniy Paltsev <Eugeniy.Paltsev@synopsys.com>
Signed-off-by: Alexey Brodkin <abrodkin@synopsys.com>
Previous SLC management implementation is broken. Seems like it was
never sufficiently tested probably because most of the time IOC was used
instead (i.e. no manual cache operations were done).
Now if we disable IOC in U-boot we'll get a lot of errors while using
DMA-enabled peripherals.
This time we fix it by substitution of broken per-line SLC operations
region operations as it is done in the Linux kernel (we took it from
v4.14 which is the latest stable as of today).
Among other things this implementation might be a bit faster because
instead of iteration over each and every cache line we're taking care
about entire region in one go.
Main changes:
* Replaced __slc_line_op (per line operations) by __slc_rgn_op
(region operations).
* Reworked __slc_entire_op to get rid of __after_slc_op and
__before_slc_op functions.
Note flush fix (flush only instead of flush-n-inv when OP_FLUSH is
used, see [1] for more details) is already incorporated here.
* Added SLC invalidation to invalidate_icache_all().
* Added (start >= end) check to invalidate_dcache_range() and
flush_dcache_range() as some buggy drivers pass region start == end.
* Added read-out of MMU BCR so we may know if PAE40 exists in HW and then
act on a particular AUX regs accordingly.
[1] http://lists.infradead.org/pipermail/linux-snps-arc/2018-January/003357.html
Signed-off-by: Eugeniy Paltsev <Eugeniy.Paltsev@synopsys.com>
Signed-off-by: Alexey Brodkin <abrodkin@synopsys.com>
dcache_exists, icache_exists, slc_exists and ioc_exists global
variables in "arch/arc/lib/cache.c" remain uninitialized if
SoC doesn't have corresponding HW.
This happens because we use the next constructions for their
definition and initialization:
-------------------------->>---------------------
int ioc_exists __section(".data");
if (/* condition */)
ioc_exists = 1;
-------------------------->>---------------------
That's quite a non-trivial issue as one may think of it.
The point is we intentionally put those variables in ".data" section
so they might survive relocation (remember we initilaize them very early
before relocation and continue to use after reloaction). While being
non-initialized and not explicitly put in .data section they would end-up
in ".bss" section which by definition is filled with zeroes.
But since we place those variables in .data section we need to care
about their proper initialization ourselves.
Also while at it we change their type to "bool" as more appropriate.
Signed-off-by: Eugeniy Paltsev <Eugeniy.Paltsev@synopsys.com>
Signed-off-by: Alexey Brodkin <abrodkin@synopsys.com>
As per ARC HS databook (see chapter 5.3.3.2) it is required to add
3 NOPs after each write to IC_IVIC which we do from now on.
Signed-off-by: Alexey Brodkin <abrodkin@synopsys.com>
Cc: Eugeniy Paltsev <paltsev@synopsys.com>
Currently slave cores will be kick-started even if we want
to dry run bootm which is not what we really want.
Signed-off-by: Alexey Brodkin <abrodkin@synopsys.com>
Cc: Eugeniy Paltsev <paltsev@synopsys.com>
We are now using an env_ prefix for environment functions. Rename these
two functions for consistency. Also add function comments in common.h.
Quite a few places use getenv() in a condition context, provoking a
warning from checkpatch. These are fixed up in this patch also.
Suggested-by: Wolfgang Denk <wd@denx.de>
Signed-off-by: Simon Glass <sjg@chromium.org>
We used to use the same memory layout and size for a couple of
boards and thus we just hardcoding IOC aperture start and size.
Now when we're getting more boards with more memory on board we
need to have an ability to set IOC so it matches real DDR layout
and size.
Even though it is not really a must but for simplicity we assume
IOC covers all the DDR we have, that gives us a chance to not
bother where DMA buffers are allocated - any part of DDR is OK.
Signed-off-by: Alexey Brodkin <abrodkin@synopsys.com>
ARCompact cores are not supposed to be used in SMP designs
(this doesn't stop people from creation of heterogeneous chips,
for an example keep reading) so there's no point in
checking ARCNUM and halting somebody if we build for ARC700.
Moreover on AXS101 board we have ARC770 in the ASIC together with
other ARC cores and ARC770 happens to be the last node in JTAG chain
with ARCNUM = 4. And existing check halts the one and only core we
want keep running.
Signed-off-by: Alexey Brodkin <abrodkin@synopsys.com>
This allows us to use the same DRAM init function on all archs. Add a
dummy function for arc, which does not use DRAM init here.
Signed-off-by: Simon Glass <sjg@chromium.org>
[trini: Dummy function on nios2]
Signed-off-by: Tom Rini <trini@konsulko.com>
As reported in STAR 9001165532, an SLC control reg read (for checking
busy state) right after SLC invalidate command may incorrectly return
NOT busy causing software to NOT spin-wait while operation is underway.
(and for some reason this only happens if L1 cache is also disabled - as
required by IOC programming model)
Suggested workaround is to do an additional Control Reg read, which
ensures the 2nd read gets the right status.
Same fix made in Linux kernel:
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=c70c473396cbdec1168a6eff60e13029c0916854
Signed-off-by: Alexey Brodkin <abrodkin@synopsys.com>
Even though we expect only master core to execute U-Boot code
let's make sure even if for some reason slave cores attempt to
execute U-Boot in parallel with master they get halted very early.
If platform wants it may kick-start slave cores before passing control
to say Linux kernel or any other application that want to see all cores
of SMP SoC up and running.
Signed-off-by: Alexey Brodkin <abrodkin@synopsys.com>
This commit replaces legacy timer code with usage of arc timer
driver.
It removes arch/arc/lib/time.c file and selects CONFIG_CLK,
CONFIG_TIMER and CONFIG_ARC_TIMER options for all ARC boards by default.
Therefore we remove CONFIG_CLK option from less common axs101 and
axs103 defconfigs.
Also it removes legacy CONFIG_SYS_TIMER_RATE config symbol from
axs10x.h, tb100.h and nsim.h configs files as it is no longer required.
Signed-off-by: Vlad Zakharov <vzakhar@synopsys.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
Commit e2f88dfd2d ("libfdt: Introduce new ARCH_FIXUP_FDT option")
allows us to skip memory setup of DTB, but a problem for ARM is that
spin_table_update_dt() and psci_update_dt() are skipped as well if
CONFIG_ARCH_FIXUP_FDT is disabled.
This commit allows us to skip only fdt_fixup_memory_banks() instead
of the whole of arch_fixup_fdt(). It will be useful when we want to
use a memory node from a kernel DTB as is, but need some fixups for
Spin-Table/PSCI.
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Acked-by: Alexey Brodkin <abrodkin@synopsys.com>
Acked-by: Simon Glass <sjg@chromium.org>
Fixed build error for x86:
Signed-off-by: Simon Glass <sjg@chromium.org>
Starting from arc-2016.03 GNU tools linker properly works with
symbols defined in linker script and so external declarations
are no longer required, dump them.
Signed-off-by: Alexey Brodkin <abrodkin@synopsys.com>
Initially IVT for ARCv2 was simply copypasted from ARCompact
with some selected fixes so basic stuff works.
Now we update it with more ARCv2 specific vectors like
* Software Interrupt
* Division by zero
* Data cache consistency error
* Misaligned access
Also normal interrupts are now implemented properly and extened to
all possible 240 items.
Signed-off-by: Alexey Brodkin <abrodkin@synopsys.com>
This might be useful to make sure relocation fixups really
happen. And since this info gets printed only in DEBUG
build it doesn't really hurt normal execution.
Signed-off-by: Alexey Brodkin <abrodkin@synopsys.com>
According to ARC HS databook it is required to flush and disable
caches prior programming IOC registers. Otherwise ongoing coherent
memory operations may not observe the coherency protocols as
expected.
But since in ARC HS v2.1 there's no way to disable SLC (AKA L2 cache)
we're doing our best flushing and invalidating it.
Signed-off-by: Alexey Brodkin <abrodkin@synopsys.com>
invalidate_dcache_all() could be used in different use-cases
and what is especially important most of those cases won't be
related to DMAed data to or from peripherals, i.e. we'll be doing
invalidation of data used purely by CPU cores.
Given that IOC engine only snoops data that goes through DMA
we need to care ourselves about data used only by CPU cores
and so remove dependency on IOC from invalidate_dcache_all()
and always do real invalidation.
Signed-off-by: Alexey Brodkin <abrodkin@synopsys.com>
flush_dcache_all() is used in the very end of U-Boot self relocation
to write back all copied and then patched code and data to their
new location in the very end of available memory space.
Since that has nothing to do with IO (i.e. no external DMA happens
here) IOC won't help here and we need to write back data cache contents
manually.
Signed-off-by: Alexey Brodkin <abrodkin@synopsys.com>
ISS is obsolete now and nSIM is used for simulation instead.
In its turn nSIM properly handles baud-rate settings so get rid
of now useless check.
Signed-off-by: Alexey Brodkin <abrodkin@synopsys.com>
With release of ARC HS38 v2.1 new IO coherency engine could be built-in
ARC core. This hardware module ensures coherency between DMA-ed data
from peripherals and L2 cache.
With L2 and IOC enabled there's no overhead for L2 cache manual
maintenance which results in significantly improved IO bandwidth.
Signed-off-by: Alexey Brodkin <abrodkin@synopsys.com>
ARC core could be configured with different L1 and L2 (AKA SLC) cache
line lengths. At least these values are possible and were really used:
32, 64 or 128 bytes.
Current implementation requires cache line to be selected upon U-Boot
configuration and then it will only work on matching hardware. Indeed
this is quite efficient because cache line length gets hardcoded during
code compilation. But OTOH it makes binary less portable.
With this commit we allow U-Boot to determine real L1 cache line length
early in runtime and use this value later on. This extends portability
of U-Boot binary a lot.
Signed-off-by: Alexey Brodkin <abrodkin@synopsys.com>
board_init_f_mem() alters the C runtime environment's
stack it is actually already using. This is not a valid
behaviour within a C runtime environment.
Split board_init_f_mem into C functions which do not alter
their own stack and always behave properly with respect to
their C runtime environment.
Signed-off-by: Albert ARIBAUD <albert.u.boot@aribaud.net>
Acked-by: Thomas Chou <thomas@wytron.com.tw>
[1] Align cache management functions to those in Linux kernel. I.e.:
a) Use the same functions for all cache ops (D$ Inv/Flush)
b) Split cache ops in 3 sub-functions: "before", "lineloop" and
"after". That way we may re-use "before" and "after" functions for
region and full cache ops.
[2] Implement full-functional L2 (SLC) management. Before SLC was
simply disabled early on boot. It's also possible to enable or disable
L2 cache from config utility.
[3] Disable/enable corresponding caches early on boot. So if U-Boot is
configured to use caches they will be used at all times (this is useful
in partucular for speed-up of relocation).
Signed-off-by: Alexey Brodkin <abrodkin@synopsys.com>
With new SMP-enabled CPUs with ARC HS38 cores and corresponding support
in Linux kernel it's required to add basic SMP support in U-Boot.
Currently we assume the one and only core starts execution after
power-on. So most of things in U-Boot is handled in UP mode.
But when U-Boot is used for loading and starting Linux kernel right
before jumping to kernel's entry point U-Boot:
[1] Sets all slave cores to jump to the same address [kernel's entry
point]
[2] Really starts all slav cores
In ARC's implemetation of SMP in Linux kernel all cores are supposed to
run the same start-up code. But only core with ID 0 (master core)
processes further while others are looping waiting for master core to
complete some initialization.
That means it's safe to un-pause slave cores and let them execute kernel
- they will wait for master anyway.
Signed-off-by: Alexey Brodkin <abrodkin@synopsys.com>
Cc: Vineet Gupta <vgupta@synopsys.com>
While testing "arc: make sure _start is in the beginning of .text
section" I haven't done proper clean-up of built binaries and so missed
another tiny bit that lead to the following error:
--->8---
LD u-boot
arc-linux-ld.bfd: cannot find arch/arc/lib/start.o
Makefile:1107: recipe for target 'u-boot' failed
make: *** [u-boot] Error 1
--->8---
Fix is trivial: put "start.o" in "extra-y".
Signed-off-by: Alexey Brodkin <abrodkin@synopsys.com>
This is important to have entry point in the beginning of .text section
because it allows simple loading and execution of U-Boot.
For example pre-bootloader loads U-Boot in memory starting from offset
0x81000000 and then just jumps to the same address.
Otherwise pre-bootloader would need to find-out where entry-point is. In
its turn if it deals with binary image of U-Boot there's no way for
pre-bootloader to get required value.
Signed-off-by: Alexey Brodkin <abrodkin@synopsys.com>
ARCv2 cores may have built-in SLC (System Level Cache, AKA L2-cache).
This change adds functions required for controlling SLC:
* slc_enable/disable
* slc_flush/invalidate
For now we just disable SLC to escape DMA coherency issues until either:
* SLC flush/invalidate is supported in DMA APIin U-Boot
* hardware DMA coherency is implemented (that might be board specific
so probably we'll need to have a separate Kconfig option for
controlling SLC explicitly)
Signed-off-by: Alexey Brodkin <abrodkin@synopsys.com>
As discussed on mailing list we're drifting away from
CONFIG_SYS_GENERIC_GLOBAL_DATA in favour to use of board_init_f_mem()
for global data.
So do this for ARC architecture.
Signed-off-by: Alexey Brodkin <abrodkin@synopsys.com>
Intention behind this work was elimination of as much assembly-written
code as it is possible.
In case of ARC we already have relocation fix-up implemented in C so why
don't we use C for U-Boot copying, .bss zeroing etc.
It turned out x86 uses pretty similar approach so we re-used parts of
code in "board_f.c" initially implemented for x86.
Now assembly usage during init is limited to stack- and frame-pointer
setup before and after relocation.
Signed-off-by: Alexey Brodkin <abrodkin@synopsys.com>
Cc: Simon Glass <sjg@chromium.org>
This separation makes maintenance of code easier because those low-level
interrupt- or exception handling routines are pretty static and usually
require not much care while start-up code is a subject of modifications
and enhancements.
Signed-off-by: Alexey Brodkin <abrodkin@synopsys.com>
Even though ARCompact and ARCv2 are not binary compatible most of
assembly instructions are used in both. With this change we'll get rid
of duplicate code.
Still IVTs are implemented differently so we're keeping them in separate
files.
Signed-off-by: Alexey Brodkin <abrodkin@synopsys.com>
always
Make both invalidate_icache_all() and invalidate_dcache_all() available
even if U-Boot is configured with CONFIG_SYS_DCACHE_OFF and/or
CONFIG_SYS_ICACHE_OFF.
This is useful because configuration of U-Boot may not match actual
hardware features. Real board may have cache(s) but for some reason we
may want to run U-Boot with cache(s) disabled (for example if some
peripherals work improperly with existing drivers if data cache is
enabled). So board may start with cache(s) enabled (that's the case for
ARC cores with built-in caches) but early in U-Boot we disable cache(s)
and make sure all contents of data cache gets flushed in RAM.
Signed-off-by: Alexey Brodkin <abrodkin@synopsys.com>
This way we may have very limited set of functions implemented so we
save some space.
Also it allows us to build U-Boot for any ARC core with the same one
toolchain because we don't rely on pre-built libgcc.
For example:
* we may use little-endian toolchain but build U-Boot for ether
endianess
* we may use non-multilibbed uClibc toolchain but build U-Boot for
whatever ARC CPU flavour that current GCC supports
Private libgcc built from generic C implementation contributes only 144
bytes to .text section so we don't see significant degradation of size:
--->8---
$ arc-linux-size u-boot.libgcc-prebuilt
text data bss dec hex filename
222217 24912 214820 461949 70c7d u-boot.libgcc-prebuilt
$ arc-linux-size u-boot.libgcc-private
text data bss dec hex filename
222361 24912 214820 462093 70d0d u-boot.libgcc-private
--->8---
Also I don't notice visible performance degradation compared to
pre-built libgcc (where at least "*div*" functions are had-written in
assembly) on typical operations of downloading 10Mb uImage over TFTP and
bootm.
Signed-off-by: Alexey Brodkin <abrodkin@synopsys.com>
This change allows to keep board description clean and minimalistic.
This is especially helpful if one board may house different CPUs with
different features.
It is applicable to both FPGA-based boards or those that have CPUs
mounted on interchnagable daughter-boards.
Signed-off-by: Alexey Brodkin <abrodkin@synopsys.com>
