Free Pascal on OSv: what changed

Revision 1 to 2. Removed lines have a minus sign; added lines have a plus sign.

Old	New		Line
1	1		# OSv
2	2
3	3		OSv is an operating system based on Linux optimized for the cloud. [Official page](http://osv.io/) It runs a single application together with a small kernel and all needed libraries in a virtual machine. That means to run OSv applications you need to install a hypervisor such as QEMU/KVM or VirtualBox.
4	4
5	5		# Installation
6	6
7	7		## Install OSv on Linux
8	8
9	9		This worked on 3rd Mar 2015 on Ubuntu 14.10 and on 3rd Sep 2016 on Ubuntu 16.04:
10	10
11	11		Please read <http://osv.io/run-locally/>. Especially about the "Data collection".
12	12
13	13		Downloading capstan to ~/bin/capstan:
14	14
15		-	~~`curl `[`https://raw.githubusercontent.com/cloudius-systems/capstan/master/scripts/download`](https://raw.githubusercontent.com/cloudius-systems/capstan/master/scripts/download)` \| bash`~~
	15	+	```text
	16	+	curl https://raw.githubusercontent.com/cloudius-systems/capstan/master/scripts/download \| bash
	17	+	```
16	18
17	19		Install needed qemu-kvm (VirtualBox is also possible, but not handled in this document)
18	20
19		-	~~`sudo apt-get install qemu-kvm`~~
	21	+	```text
	22	+	sudo apt-get install qemu-kvm
	23	+	```
20	24
21	25		# Building an instance with capstan
22	26
23	27		Capstan takes a basic image and adds your libraries to create a VM image. It then starts the VM and runs the 'main' function of your library. At the moment only Linux/amd64 dynamic libraries with PIC are supported.
24	28
25	29		## Capstanfile
26	30
27	31		Capstan needs a config file named Capstanfile. Read [here](https://github.com/cloudius-systems/capstan/blob/master/Documentation/Capstanfile.md) for details.
28	32
29	33		Create a directory for the example. For instance ~/osv_fpc_test.
30	34
31	35		Here is an example config for a hello world program (~/osv_fpc_test/Capstanfile):
32	36
33	37		# Name of the base image. Capstan will download this automatically from Capstan repository.
34	38		base: cloudius/osv-base
35	39
36	40		# The command line passed to OSv to start up the application.
37	41		cmdline: /tools/hello.so
38	42
39	43		# The command used to build the application.
40	44		build: ./compile.sh
41	45
42	46		# List of files that are included in the generated image.
43	47		files:
44	48		/tools/hello.so: hello.so
45	49
46	50		## Pascal Library
47	51
48	52		The small Linux kernel does not support all syscalls needed by the default FPC Linux System unit.
49	53
50	54		See here for some details what OSv does not support: <https://github.com/cloudius-systems/osv/wiki/Porting-native-applications-to-OSv>
51	55
52	56		You need to build the System unit using Libc (tested with fpc trunk revision 34418):
53	57
54		-	~~`cd fpc_src_3.1.1`\~~
55		-	~~`make clean all OPT='-dFPC_USE_LIBC -Fl/usr/lib/gcc/x86_64-linux-gnu/5'`\~~
56		-	~~`sudo make install INSTALL_PREFIX=/usr`~~
	58	+	```text
	59	+	cd fpc_src_3.1.1
	60	+	make clean all OPT='-dFPC_USE_LIBC -Fl/usr/lib/gcc/x86_64-linux-gnu/5'
	61	+	sudo make install INSTALL_PREFIX=/usr
	62	+	```
57	63
58	64		## hello.pas
59	65
60	66		``` pascal
61	67		library hello;
62	68
63	69		// start function for OSv
64	70		function main: longint; cdecl;
65	71		begin
66	72		Writeln('It works!');
67	73		main:=0;
68	74		end;
69	75
70	76		exports main name 'main'; // OSv searches for 'main' in the library
71	77
72	78		end.
73	79		```
74	80
75	81		Here is the ~/osv_fpc_test/compile.sh:
76	82
77	83		#!/bin/bash
78	84		# create a dynamically linked library hello.so
79	85		/usr/lib/fpc/3.1.1/ppcx64 -fPIC -XD -Xc -gw2 -ohello.so hello.pas
80	86
81	87		## Building
82	88
83	89		Note: The first time you build, capstan will download the base VM image "cloudius/osv-base" (~/.capstan/).
84	90
85	91		[]$ cd ~/osv_fpc_test
86	92		[]$ ~/bin/capstan build
87	93		Building osv...
88	94		Uploading files...
89	95		1 / 1 [===================================] 100.00 %
90	96
91	97		## Running
92	98
93	99		[]$ ~/bin/capstan run
94	100		Created instance: helloworld
95	101		OSv v0.18
96	102		eth0: 192.168.122.15
97	103		It works!
98	104
99	105		# Pascal Library without using the System unit
100	106
101	107		As demonstration here is a library, that does not call the system unit (works the normal FPC system unit):
102	108
103	109		## hello.pas
104	110
105	111		Here is the ~/osv_fpc_test/hello.pas:
106	112
107	113		``` pascal
108	114		library hello;
109	115
110	116		uses
111	117		unixtype;
112	118
113	119		// use the C function 'write'
114	120		function CWrite(fd : cInt; buf:pChar; nbytes : unixtype.TSize): TSsize; external name 'write';
115	121
116	122		// start function for OSv
117	123		function main: longint; cdecl;
118	124		const
119	125		MyText: PChar = 'It works!'#10;
120	126		begin
121	127		CWrite(StdOutputHandle,MyText,strlen(MyText));
122	128		main:=0;
123	129		end;
124	130
125	131		exports main name 'main'; // OSv searches for 'main' in the library
126	132
127	133		end.
128	134		```
129	135
130	136		## Compile a library that does not call the system init
131	137
132	138		Here is the ~/osv_fpc_test/compile.sh:
133	139
134	140		#!/bin/bash
135	141
136	142		# compile without linking, create a dynamically linked library hello.so
137	143		fpc -fPIC -XD -Xc -g -s -ohello.so hello.pas
138	144		# link without -init FPC_SHARED_LIB_START -fini FPC_LIB_EXIT
139	145		/usr/bin/ld -b elf64-x86-64 -m elf_x86_64 -soname hello.so -shared -L. -o hello.so link.res
140	146
141	147		## Building
142	148
143	149		Note: The first time you build, capstan will download the base VM image "cloudius/osv-base" (~/.capstan/).
144	150
145	151		[]$ cd ~/osv_fpc_test
146	152		[]$ ~/bin/capstan build
147	153		Building osv...
148	154		Uploading files...
149	155		1 / 1 [===================================] 100.00 %
150	156
151	157		## Running
152	158
153	159		[]$ cd ~/osv_fpc_test
154	160		[]$ ~/bin/capstan run
155	161		Created instance: osv
156	162		OSv v0.18
157	163		eth0: 192.168.122.15
158	164		It works!
159	165
160	166		---
161	167		From the Free Pascal wiki, page "Free Pascal on OSv", as it stood on 2020-02-16 after a change by Trev, out of the wiki's dump of 2024-05-26. Copyright stays with the author who wrote it, according to the old wiki's [[Licensing]] page. If you have concerns about this material, [message the admin](/wiki-contact).
162	168		Category: Linux

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