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Re: [Qemu-devel] [PATCH v2 2/2] hw/i386/pc: Map into memory the initrd
From: |
Paolo Bonzini |
Subject: |
Re: [Qemu-devel] [PATCH v2 2/2] hw/i386/pc: Map into memory the initrd |
Date: |
Tue, 23 Jul 2019 16:30:17 +0200 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.8.0 |
On 23/07/19 16:04, Stefano Garzarella wrote:
> In order to reduce the memory footprint we map into memory
> the initrd using g_mapped_file_new() instead of reading it.
> In this way we can share the initrd pages between multiple
> instances of QEMU.
>
> Suggested-by: Paolo Bonzini <address@hidden>
> Signed-off-by: Stefano Garzarella <address@hidden>
Coverity is going to complain about the leaks. Should we instead store
the initrd GMappedFile in PCMachineState, even if it is just for reference?
Paolo
> ---
> hw/i386/pc.c | 15 +++++++++++----
> 1 file changed, 11 insertions(+), 4 deletions(-)
>
> diff --git a/hw/i386/pc.c b/hw/i386/pc.c
> index 549c437050..b139589777 100644
> --- a/hw/i386/pc.c
> +++ b/hw/i386/pc.c
> @@ -1241,17 +1241,20 @@ static void load_linux(PCMachineState *pcms,
>
> /* load initrd */
> if (initrd_filename) {
> + GMappedFile *gmf;
> gsize initrd_size;
> gchar *initrd_data;
> GError *gerr = NULL;
>
> - if (!g_file_get_contents(initrd_filename, &initrd_data,
> - &initrd_size, &gerr)) {
> + gmf = g_mapped_file_new(initrd_filename, false, &gerr);
> + if (!gmf) {
> fprintf(stderr, "qemu: error reading initrd %s: %s\n",
> initrd_filename, gerr->message);
> exit(1);
> }
>
> + initrd_data = g_mapped_file_get_contents(gmf);
> + initrd_size = g_mapped_file_get_length(gmf);
> initrd_max = pcms->below_4g_mem_size - pcmc->acpi_data_size
> - 1;
> if (initrd_size >= initrd_max) {
> fprintf(stderr, "qemu: initrd is too large, cannot
> support."
> @@ -1378,6 +1381,7 @@ static void load_linux(PCMachineState *pcms,
>
> /* load initrd */
> if (initrd_filename) {
> + GMappedFile *gmf;
> gsize initrd_size;
> gchar *initrd_data;
> GError *gerr = NULL;
> @@ -1387,12 +1391,15 @@ static void load_linux(PCMachineState *pcms,
> exit(1);
> }
>
> - if (!g_file_get_contents(initrd_filename, &initrd_data,
> - &initrd_size, &gerr)) {
> + gmf = g_mapped_file_new(initrd_filename, false, &gerr);
> + if (!gmf) {
> fprintf(stderr, "qemu: error reading initrd %s: %s\n",
> initrd_filename, gerr->message);
> exit(1);
> }
> +
> + initrd_data = g_mapped_file_get_contents(gmf);
> + initrd_size = g_mapped_file_get_length(gmf);
> if (initrd_size >= initrd_max) {
> fprintf(stderr, "qemu: initrd is too large, cannot support."
> "(max: %"PRIu32", need %"PRId64")\n",
>