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Save memory allocation in the elf loader

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The current elf loader uses too much memory. For example, I have a
executable with a bss section of 400 MB and I set the ram size to 512
MB. Qemu uses about 780MB of RAM (which is fine), but there's a peak at
1.6 GB during initialization (this is not fine).

This patch fixes two things:
 1) do not allocate each elf program twice.
 2) do not allocate memory for areas that are only zeros.

For this we need a new field in Rom: "datasize" which is the size of the
allocated data. If datasize is less than romsize, it means that the area
from datasize to romsize is filled with zeros.

Signed-off-by: Fabien Chouteau <chouteau@adacore.com>
Signed-off-by: Alexander Graf <agraf@suse.de>
This commit is contained in:
Fabien Chouteau 2013-02-19 04:41:11 +00:00 • committed by Alexander Graf
parent 6bbd5dde9a
commit d60fa42e8b
3 changed files with 75 additions and 21 deletions
Download patch file Download diff file Expand all files Collapse all files

19
hw/elf_ops.h
View file

@ -197,7 +197,7 @@ static int glue(load_elf, SZ)(const char *name, int fd,
struct elfhdr ehdr;
struct elf_phdr *phdr = NULL, *ph;
int size, i, total_size;
elf_word mem_size;
elf_word mem_size, file_size;
uint64_t addr, low = (uint64_t)-1, high = 0;
uint8_t *data = NULL;
char label[128];
@ -252,14 +252,16 @@ static int glue(load_elf, SZ)(const char *name, int fd,
for(i = 0; i < ehdr.e_phnum; i++) {
ph = &phdr[i];
if (ph->p_type == PT_LOAD) {
mem_size = ph->p_memsz;
/* XXX: avoid allocating */
data = g_malloc0(mem_size);
mem_size = ph->p_memsz; /* Size of the ROM */
file_size = ph->p_filesz; /* Size of the allocated data */
data = g_malloc0(file_size);
if (ph->p_filesz > 0) {
if (lseek(fd, ph->p_offset, SEEK_SET) < 0)
if (lseek(fd, ph->p_offset, SEEK_SET) < 0) {
goto fail;
if (read(fd, data, ph->p_filesz) != ph->p_filesz)
}
if (read(fd, data, file_size) != file_size) {
goto fail;
}
}
/* address_offset is hack for kernel images that are
linked at the wrong physical address. */
@ -281,7 +283,9 @@ static int glue(load_elf, SZ)(const char *name, int fd,
}
snprintf(label, sizeof(label), "phdr #%d: %s", i, name);
rom_add_blob_fixed(label, data, mem_size, addr);
/* rom_add_elf_program() seize the ownership of 'data' */
rom_add_elf_program(label, data, file_size, mem_size, addr);
total_size += mem_size;
if (addr < low)
@ -289,7 +293,6 @@ static int glue(load_elf, SZ)(const char *name, int fd,
if ((addr + mem_size) > high)
high = addr + mem_size;
g_free(data);
data = NULL;
}
}