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    SubjectRe: [PATCH v5 10/10] x86, efi: EFI boot stub support
    Hey Matt,

    On 11/24/2011 03:43 PM, Maarten Lankhorst wrote:
    > Hey Matt,
    >
    > On 11/23/2011 08:27 PM, Matt Fleming wrote:
    >
    >> On Wed, 2011-11-23 at 01:44 +0100, Maarten Lankhorst wrote:
    >>> When I tested this with v3.2-rc2 it didn't boot, it hung before it
    >>> initialized the kernel.
    >>> Without initrd it works fine, though.
    >> Bah, so this change actually makes booting worse? You said before that
    >> you almost made it to userspace but this seems to hang much earlier now.
    >> Is that correct?
    >>
    >> ... back to the drawing board.
    > I was looking at why grub2 could boot, seems to be it reads in chunks of
    > 256 kilobytes. I seem to be able to get it to boot with chunks of 4 mb
    > as well, but didn't test beyond that.
    >
    > So the fix is to simply read the file in parts, otherwise efi hangs..
    > As a nice side effect, short reads are also handled, but the efi
    > firmware seems to choke over huge reads and dies.
    So after I was encouraged by mjg59 to find out the limit,
    I put this patch to test maximum file size with together..

    Turns out that it pukes on 4 mb, my printf was fucked,
    in the patch below I corrected it, so I don't know for sure
    if that included 4 mb being bad or not. I suppose writing
    a test for read(fd, addr, 5 * 1024 * 1024) was too hard for
    efi to pass. ;)

    Just make a file with dd if=/dev/urandom of=initrd.img bs=1M count=99
    to find out when/if YOUR efi implementation will die! :D

    diff --git a/arch/x86/boot/compressed/eboot.c b/arch/x86/boot/compressed/eboot.c
    index 8627a56..415b875 100644
    --- a/arch/x86/boot/compressed/eboot.c
    +++ b/arch/x86/boot/compressed/eboot.c
    @@ -30,6 +30,19 @@
    #define PIXEL_BLT_ONLY 3
    #define PIXEL_FORMAT_MAX 4

    +typedef struct _EFI_SIMPLE_TEXT_OUTPUT_PROTOCOL {
    + void* Reset;
    + void *OutputString;
    + void *TestString;
    + void *QueryMode;
    + void *SetMode;
    + void *SetAttribute;
    + void *ClearScreen;
    + void *SetCursorPosition;
    + void *EnableCursor;
    + void *Mode;
    +} __attribute__((packed)) EFI_SIMPLE_TEXT_OUTPUT_PROTOCOL;
    +
    typedef struct {
    u32 red_mask;
    u32 green_mask;
    @@ -692,17 +705,27 @@ grow:

    addr = initrd_addr;
    for (j = 0; j < nr_initrds; j++) {
    - u64 size;
    -
    - size = initrds[j].size;
    - status = efi_call_phys3(fh->read, initrds[j].handle,
    - &size, addr);
    - if (status != EFI_SUCCESS)
    - goto free_initrd_total;
    -
    + u64 size, chunksize;
    + uint16_t str[] = { 'S', 'i', 'z', 'e', ':', ' ', ' ',' ', ' ', '\r', '\n', 0 };
    + EFI_SIMPLE_TEXT_OUTPUT_PROTOCOL *output = (void*)sys_table->stderr;
    +
    + for (chunksize = 1024 * 1024; chunksize < initrds[j].size; chunksize += 1024 * 1024) {
    + str[5] = ((chunksize / 1024 / 1024) / 10) + '0';
    + str[6] = ((chunksize / 1024 / 1024) % 10) + '0';
    + efi_call_phys2(output->OutputString, sys_table->stderr_handle, str);
    + size = initrds[j].size;
    + efi_call_phys2(fh->set_position, initrds[j].handle, 0);
    + while (size) {
    + u64 toread = size > chunksize ? chunksize : size;
    + status = efi_call_phys3(fh->read, initrds[j].handle,
    + &toread, addr);
    + if (status != EFI_SUCCESS)
    + goto free_initrd_total;
    + size -= toread;
    + addr += toread;
    + }
    + }
    efi_call_phys1(fh->close, initrds[j].handle);
    -
    - addr += size;
    }

    }



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