Build H2 with Picolibc by quic-k · Pull Request #10 · qualcomm/hexagon-hypervisor

quic-k · 2026-04-20T09:45:33Z

No description provided.

colmode

Looks good overall, but we might want to merge this after erich's makefile changes rather than the other way around.

quic-k · 2026-05-05T14:28:55Z

+	r1 = #__boot_net_phys_offset__
+	memw(r1) = r0
+	jump _start          // picolibc CRT entry (replaces hexagon_pre_main)
+


we can, but since we are not including any C header, we don't have __PICOLIBC__
so for simplicity I created 2 files

maybe I will have to use the PICOLIBC=1 flag to define a macro, which we can use
or do you have something else in mind?

"PICOLIBC=1 flag to define a macro", yes. But since this is all transitional and we'll eventually use only pico I think that leaving it as is would be fine.

quic-k · 2026-05-05T14:28:55Z

+	r1 = #__boot_net_phys_offset__
+	memw(r1) = r0
+	jump _start          // picolibc CRT entry (replaces hexagon_pre_main)
+


we can, but since we are not including any C header, we don't have __PICOLIBC__
so for simplicity I created 2 files

maybe I will have to use the PICOLIBC=1 flag to define a macro, which we can use
or do you have something else in mind?

quic-k · 2026-05-05T14:32:03Z

Looks good overall, but we might want to merge this after erich's makefile changes rather than the other way around.

thanks for the review, ping me whenever that is merged, I will have to resolve merge conflicts

Also, we don't yet have a way to run unit tests with pico since those tools aren't on github. Best to run make testall locally and then comment here when it passes.

sure, so far I have built H2 successfully and used the install artifacts to run Picolibc testsuite which passes
will look into getting H2 unit tests working with Picolibc

bryanb-h2 · 2026-05-05T14:39:46Z

Looks good overall, but we might want to merge this after erich's makefile changes rather than the other way around.

Hey, look; our first comment from a non-qc account :)

quic-k · 2026-05-07T10:34:33Z

why is hexagon_standalone.h being used? @bryanb-h2

hexagon-hypervisor/kernel/util/stmode/test/test.c

Line 12 in f74ebc7

#include <hexagon_standalone.h>

hexagon-hypervisor/kernel/util/spinlock/test/test.c

Line 10 in f74ebc7

#include <hexagon_standalone.h>

bryanb-h2 · 2026-05-07T10:48:04Z

why is hexagon_standalone.h being used? @bryanb-h2

hexagon-hypervisor/kernel/util/stmode/test/test.c

Line 12 in f74ebc7

#include <hexagon_standalone.h>

hexagon-hypervisor/kernel/util/spinlock/test/test.c

Line 10 in f74ebc7

#include <hexagon_standalone.h>

Because most of the unit tests run with standalone with a test harness for testing only one function -- avoids booting the kernel to simplify debug. We need a substitute for standalone but we haven't addressed this yet. The unit tests don't even use features of standalone. Using the default dinkum build is just a convenient way to link with crt0 and get to main(). We actually have a min_crt0 in the h2 repo. Just need to dust that off and change how we link unit tests.

Here it is, entirely:

/*

Copyright (c) Qualcomm Technologies, Inc. and/or its subsidiaries.
SPDX-License-Identifier: BSD-3-Clause-Clear
*/

.section .start,"awx",@progbits

.global _start

.global hexagon_pre_main

#_start:

jump start

hexagon_pre_main:
r0 = ##SDA_BASE
gp = r0
r29 = ##stack
{
r0 = r29
r1 = #1
call main
}

jump start

.data
.p2align 8
.space 1024

stack:
.word stack
.word 0

quic-k · 2026-05-07T11:10:11Z

Because most of the unit tests run with standalone with a test harness for testing only one function -- avoids booting the kernel to simplify debug.

yeah, for debugging that is better, but booter tests would have been easier for me to get passing

We need a substitute for standalone but we haven't addressed this yet. The unit tests don't even use features of standalone. Using the default dinkum build is just a convenient way to link with crt0 and get to main(). We actually have a min_crt0 in the h2 repo. Just need to dust that off and change how we link unit tests.

is this planned to be done soon? or am I supposed to do this in this PR? maybe I could but this sounds like lot of debugging
:\

bryanb-h2 · 2026-05-07T11:26:09Z

Because most of the unit tests run with standalone with a test harness for testing only one function -- avoids booting the kernel to simplify debug.

yeah, for debugging that is better, but booter tests would have been easier for me to get passing

We need a substitute for standalone but we haven't addressed this yet. The unit tests don't even use features of standalone. Using the default dinkum build is just a convenient way to link with crt0 and get to main(). We actually have a min_crt0 in the h2 repo. Just need to dust that off and change how we link unit tests.

is this planned to be done soon? or am I supposed to do this in this PR? maybe I could but this sounds like lot of debugging :\

Not unless you're really keen to do it. I just filed QDSP-57392 for this.

.

bryanb-h2

The merge conflicts with master were complicated in some places. Please check if I screwed something up.

bryanb-h2 · 2026-05-19T20:05:52Z

 	}

-	if (NULL == (pmap->base.raw = (h2_u32_t)realloc((void *)(pmap->base.raw), sizeof(H2K_linear_fmt_t) * (end + npages + 1)))) {
+	if (0 == (pmap->base.raw = (h2_u32_t)realloc((void *)(pmap->base.raw), sizeof(H2K_linear_fmt_t) * (end + npages + 1)))) {


booter.c:673:11: warning: comparison between pointer and integer ('void *' and 'h2_u32_t' (aka 'unsigned int')) [-Wpointer-integer-compare] 673 | if (NULL == (pmap->base.raw = (h2_u32_t)realloc((void *)(pmap->base.raw), sizeof(H2K_linear_fmt_t) * (end + npages + 1)))) { | ~~~~ ^ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

So pico defines NULL differently? I thought that def was part of the tools and we don't get the same warning when building with the existing dinkum tools.

in Pico toolchain NULL in preprocessed to ((void*)0) (comes from clang's stddef.h)
existing tools might be just defining NULL to 0

Ok, then the right thing to do is probably this, which works with dinkum also:

diff --git a/booter/booter.c b/booter/booter.c
index 071702bc6..93fcf9adc 100644
--- a/booter/booter.c
+++ b/booter/booter.c
@@ -670,7 +670,7 @@ void add_linear_trans(unsigned int idx, unsigned long va, unsigned long long pa,
vm_params[idx].pmap_added = 1;
}

if (NULL == (pmap->base.raw = (h2_u32_t)realloc((void *)(pmap->base.raw), sizeof(H2K_linear_fmt_t) * (end + npages + 1)))) {

if (NULL == (void *)(pmap->base.raw = (h2_u32_t)realloc((void *)(pmap->base.raw), sizeof(H2K_linear_fmt_t) * (end + npages + 1)))) {
error("realloc pmap->base", NULL);
}
base = (H2K_linear_fmt_t *)(pmap->base.raw);

bryanb-h2 · 2026-05-19T20:07:13Z


-CFLAGS = $(OPTIMIZE) -mv$(TOOLARCH) -DARCHV=$(ARCHV) -Wall -Werror -Wno-builtin-requires-header -g -I. -I$(INSTALLPATH)/include -I$(KERNEL_BUILD_DIR)/include
-LDFLAGS = -L$(INSTALLPATH)/lib -moslib=h2 -Qunused-arguments
+ifeq ($(PICOLIBC),1)


How about pulling all these if pico sections into one make include file?

sure, I could do something like that
but maybe I should wait till H2 unit tests are cleaned up, so I don't have to rebase multiple times?

Replace all patsubst %/install,%/build/...,$(INSTALLPATH) expressions with $(INSTALLPATH)/../build/... across kernel, libs, booter, and stake Makefiles so that a user-supplied INSTALLPATH without a trailing /install no longer causes same-file cp errors, circular dependencies, or missing generated headers. Signed-off-by: Kushal Pal <kushpal@qti.qualcomm.com>

libs/locks and libs/syscall/wrapper were writing .o files and archives directly into the source tree. Add BUILD_DIR := $(INSTALLPATH)/../build/... to both Makefiles and update libs/Makefile to reference the archives from the build tree rather than the source tree. Signed-off-by: Kushal Pal <kushpal@qti.qualcomm.com>

Signed-off-by: Kushal Pal <kushpal@qti.qualcomm.com>

quic-k

I have rebased on master

quic-k · 2026-05-20T11:24:52Z

 	}

-	if (NULL == (pmap->base.raw = (h2_u32_t)realloc((void *)(pmap->base.raw), sizeof(H2K_linear_fmt_t) * (end + npages + 1)))) {
+	if (0 == (pmap->base.raw = (h2_u32_t)realloc((void *)(pmap->base.raw), sizeof(H2K_linear_fmt_t) * (end + npages + 1)))) {


booter.c:673:11: warning: comparison between pointer and integer ('void *' and 'h2_u32_t' (aka 'unsigned int')) [-Wpointer-integer-compare] 673 | if (NULL == (pmap->base.raw = (h2_u32_t)realloc((void *)(pmap->base.raw), sizeof(H2K_linear_fmt_t) * (end + npages + 1)))) { | ~~~~ ^ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

quic-k · 2026-05-20T11:27:01Z


-CFLAGS = $(OPTIMIZE) -mv$(TOOLARCH) -DARCHV=$(ARCHV) -Wall -Werror -Wno-builtin-requires-header -g -I. -I$(INSTALLPATH)/include -I$(KERNEL_BUILD_DIR)/include
-LDFLAGS = -L$(INSTALLPATH)/lib -moslib=h2 -Qunused-arguments
+ifeq ($(PICOLIBC),1)


sure, I could do something like that
but maybe I should wait till H2 unit tests are cleaned up, so I don't have to rebase multiple times?

quic-k requested review from andreykarpenko-qc and bryanb-h2 April 20, 2026 09:45

colmode previously requested changes May 5, 2026

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quic-k commented May 5, 2026

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bryanb-h2 requested changes May 19, 2026

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quic-k added 3 commits May 20, 2026 16:43

Build H2 with Picolibc

d68962a

Signed-off-by: Kushal Pal <kushpal@qti.qualcomm.com>

quic-k force-pushed the build-with-pico branch from 786255c to d68962a Compare May 20, 2026 11:21

quic-k commented May 20, 2026

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quic-k commented May 5, 2026

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.global _start

jump start

jump start

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